Tracking Upstream Updates
It's not an easy task for a maintainer to track when his or her port is updated.
Many projects, like FreeBSD itself, have some kind of announce mailing-list. You should subscribe to it and watch your inbox for new versions.
The list of unmaintained ports with an outstanding update may be of interest:
The service also sends out notifications via e-mail when updates are found. Contact Shaun or Martin to opt-in to this.
See SourceForge, but the list is in the Summary section, not Files.
There's a page with recently updated modules. You'll have to watch it in order to stay current: http://search.cpan.org/recent
There should be a better way involving automated processing of the recent file against a list of CPAN modules you maintain. It will appear here later.
Many projects are listed on FreshMeat. Every projects has a link named Subscribe to new releases after its description. The release announcement usually lag by a matter of days to months.
There are RSS feeds available at https://addons.mozilla.org/feeds.php named Recently Updated.
Not clear yet
In the Files section of each project there's a list of packages named Latest File Releases, each with a monitor button to the right. Press the button to start tracking a particular package. You'll get a mail for each new release, but you won't get any notification if a new package appears in the project. Some projects release new versions as separate packages, making this monitor feature useless. You must be logged in in order to be able to subscribe.
Use other package management systems
You can track updates to separate ports at http://gentoo-portage.com/