with this parameter set 
1) any file newer then TIME (>=) will not be deleted at dest
2) any file older then TIME (<) will not be added to dest

some workaround for directories add (file in dir newer or older) added.

--------------------------------------------------------------------
*** work/rsync-3.0.7/options.c.orig	2009-12-22 00:40:41.000000000 +0200
--- work/rsync-3.0.7/options.c	2010-07-09 15:16:22.000000000 +0300
***************
*** 165,170 ****
--- 165,171 ----
  char *rsync_path = RSYNC_PATH;
  char *backup_dir = NULL;
  char backup_dir_buf[MAXPATHLEN];
+ long check_point = -1;
  char *sockopts = NULL;
  int rsync_port = 0;
  int compare_dest = 0;
***************
*** 325,330 ****
--- 326,332 ----
    rprintf(F," -b, --backup                make backups (see --suffix & --backup-dir)\n");
    rprintf(F,"     --backup-dir=DIR        make backups into hierarchy based in DIR\n");
    rprintf(F,"     --suffix=SUFFIX         set backup suffix (default %s w/o --backup-dir)\n",BACKUP_SUFFIX);
+   rprintf(F,"     --check-point=FILE      don't delete files newer than FILE\n");
    rprintf(F," -u, --update                skip files that are newer on the receiver\n");
    rprintf(F,"     --inplace               update destination files in-place (SEE MAN PAGE)\n");
    rprintf(F,"     --append                append data onto shorter files\n");
***************
*** 609,614 ****
--- 611,617 ----
    {"backup",          'b', POPT_ARG_VAL,    &make_backups, 1, 0, 0 },
    {"no-backup",        0,  POPT_ARG_VAL,    &make_backups, 0, 0, 0 },
    {"backup-dir",       0,  POPT_ARG_STRING, &backup_dir, 0, 0, 0 },
+   {"check-point",      0,  POPT_ARG_INT,    &check_point, 0, 0, 0 },
    {"suffix",           0,  POPT_ARG_STRING, &backup_suffix, 0, 0, 0 },
    {"list-only",        0,  POPT_ARG_VAL,    &list_only, 2, 0, 0 },
    {"read-batch",       0,  POPT_ARG_STRING, &batch_name, OPT_READ_BATCH, 0, 0 },
***************
*** 1924,1929 ****
--- 1927,1938 ----
  		args[ac++] = backup_dir;
  	}
  
+ 	if (check_point >= 0) {
+ 		if (asprintf(&arg, "--check-point=%d", check_point) < 0)
+ 			goto oom;
+ 		args[ac++] = arg;
+ 	}
+ 
  	/* Only send --suffix if it specifies a non-default value. */
  	if (strcmp(backup_suffix, backup_dir ? "" : BACKUP_SUFFIX) != 0) {
  		/* We use the following syntax to avoid weirdness with '~'. */



--------------------------------------------------------------------
*** work/rsync-3.0.7/generator.c.orig	2009-12-23 21:36:27.000000000 +0200
--- work/rsync-3.0.7/generator.c	2010-07-09 15:36:01.000000000 +0300
***************
*** 96,101 ****
--- 96,102 ----
  extern char *backup_dir;
  extern char *backup_suffix;
  extern int backup_suffix_len;
+ extern long check_point;
  extern struct file_list *cur_flist, *first_flist, *dir_flist;
  extern struct filter_list_struct daemon_filter_list;
  
***************
*** 132,138 ****
  };
  
  enum delret {
!     DR_SUCCESS = 0, DR_FAILURE, DR_AT_LIMIT, DR_NOT_EMPTY
  };
  
  /* Forward declarations. */
--- 133,139 ----
  };
  
  enum delret {
!     DR_SUCCESS = 0, DR_FAILURE, DR_AT_LIMIT, DR_NOT_EMPTY, DR_NEWER
  };
  
  /* Forward declarations. */
***************
*** 160,165 ****
--- 161,192 ----
  	char *what;
  	int ok;
  
+ 	struct stat attrib;	
+ 	stat(fbuf, &attrib);	
+ 	if ( (check_point>=0)&&(check_point <= attrib.st_mtime) ) {
+ 		//if (!S_ISDIR(mode)) { 
+ 			if (verbose > 0) {
+ 				rprintf(FINFO, "checkpoint: new item (%s), deletion skiped", fbuf);
+ 				rprintf(FINFO, verbose > 1 ? " (%d <= %d)\n" : "\n", check_point, attrib.st_mtime );
+ 			}
+ 			return DR_NEWER;
+ 		//}
+ 		/*
+ 		DIR *d = opendir(fbuf);
+ 		struct dirent *p;
+ 		int is_empty = 1;
+ 		while ((is_empty>0)&&(p=readdir(d))) {
+ 			if (!strcmp(p->d_name, ".") || !strcmp(p->d_name, "..")) continue;
+ 			is_empty = 0;
+ 		}
+ 		closedir(d);
+ 		if ((is_empty>0)&&(verbose > 0)) {
+ 			rprintf(FINFO, "empty dir (%s) is newer", fbuf);
+ 			rprintf(FINFO, verbose > 1 ? " (%d <= %d)\n" : "\n", check_point, attrib.st_mtime );
+ 		}
+ 		*/
+ 	}
+ 
  	if (verbose > 2) {
  		rprintf(FINFO, "delete_item(%s) mode=%o flags=%d\n",
  			fbuf, (int)mode, (int)flags);
***************
*** 1369,1374 ****
--- 1396,1409 ----
  		stat_errno = errno;
  	}
  
+ 	if ( (check_point>=0)&&(statret != 0)&&(check_point > file->modtime) ) {
+ 		if (verbose > 0) {
+ 			rprintf(FINFO, is_dir ? "checkpoint: old directory (%s)" : "checkpoint: old item (%s), creation skipped", fname);
+ 			rprintf(FINFO, verbose > 1 ? " (%d > %d)\n" : "\n", check_point, file->modtime);
+ 		}
+ 		if ( !is_dir ) return;
+ 	}
+ 
  	if (ignore_non_existing > 0 && statret == -1 && stat_errno == ENOENT) {
  		if (is_dir) {
  			if (is_dir < 0)


--------------------------------------------------------------------
USAGE example

DEBUG=0

src=asfasfasfasfa
dest=sfasfasf

if [ ! -d $src ]; then
	req=1
fi
if [ ! -d $dest ]; then
	req=1
fi
if [ $req ]; then
	echo "SRC and DST required"
	exit 1
fi
exit

if [ "$1" != "" ]; then
	echo RECREATE ITEMS IN HOME.....
	date
	rm -rf /$dest/OLD*
	touch /$dest/NEW
	rm -rf /$dest/NEWDIR
	mkdir /$dest/NEWDIR
	touch -t 200808080808 /$dest/NEWDIR/OLD-IN-NEW
	touch /$dest/NEWDIR
	sleep 1

	rm -rf /$src/NEW*
	touch -t 200808080808 /$src/OLD
	rm -rf /$src/OLDDIR
	mkdir /$src/OLDDIR
	touch /$src/OLDDIR/NEWINOLD
	touch -A 010101 /$src/OLDDIR/NEW-IN-OLD
	touch -t 200808080808 /$src/OLDDIR

	echo "		SRC LIST --------------------------------------"
	ls -laTG /$src/
	ls -laTG /$src/OLDDIR/NEW-IN-OLD
	echo "		DEST LIST --------------------------------------"
	ls -laTG /$dest/
	ls -laTG /$dest/NEWDIR/OLD-IN-NEW
	echo "		--------------------------------------"
fi

synchronize() {

	logfile=/home/.rsync.$1.log
	lastrun=/home/.rsync.$1.lastrun
	started=/home/.rsync.$1.started

	if [ -f $lastrun ]; then
		checkpoint=$(stat -f %m $lastrun)
		mv $lastrun $lastrun~
	fi

	rm -f $logfile
	if [ -f $started ]; then
		rm -f $started
	fi
	touch $started
	rsync $verbose --delete --recursive \
		-v --log-file=$logfile \
		--check-point=$checkpoint \
		--backup-dir=$4 --backup \
		--prune-empty-dirs --links --perms --owner --group --times \
		--exclude=.rsync** \
		$2 $3
	rsyncExitCode=$?
	if [ $rsyncExitCode -gt 0 ]; then
		cat $logfile
		echo "rsync exit code is $rsyncExitCode" 
		exit $rsyncExitCode
	fi
	mv $started $lastrun
}

synchronize home.to.root /home/ 172.16.4.32::rhome /.rsync.backup
synchronize root.to.home 172.16.4.32::rhome /home/ /home/.rsync.backup

if [ "$1" != "" ]; then
	echo "		SRC LIST --------------------------------------"
	ls -laTG /$src/
	ls -laTG /$src/OLDDIR/NEW-IN-OLD
	echo "		DEST LIST --------------------------------------"
	ls -laTG /$dest/
	ls -laTG /$dest/NEWDIR/OLD-IN-NEW
	echo "		--------------------------------------"
fi