Use terminal-notifier to post Subversion status information into OS X Mountain Lion's notification center.

SVNStatus.php

<?php

/*
Requires:
  terminal-notifier - A ruby gem that talks to notification center
  launchd/cron - to schedule `php /path/to/SVNStatus.php` to run.
*/

// Config
$binary = '/path/to/bin/terminal-notifier';
$projects = array(
	array('repo_path' => '/path/to/repo', 'browse_path' => 'http://svnbrowse.yourdomain.com/r%d')
);

foreach ($projects as $project):
	$output = shell_exec('svn stat -u ' . $project['repo_path']);
	$lines = explode("\n", $output);

	if (count($lines) > 2):
		// Figure out what the last revision was
		$lastkey = array_pop(array_keys($lines));
		$last_revision = trim(str_replace('Status against revision:', '', $lines[$lastkey-1]));

		$repo_path = sprintf('%s', $project['repo_path']);
		$browse_path = sprintf($project['browse_path'], $last_revision);
		$message = sprintf('Your local copy is out of date. Latest version: %d', $last_revision);
		
		$cmd = sprintf('%s -message "%s" -title "%s" -group "%s" -open %s', $binary, $message, $repo_path, md5($repo_path), $browse_path);
		print $cmd . PHP_EOL;
		shell_exec($cmd);
	endif;
endforeach;