I just realized I didn't announce this in-forum yet, so I'll do so now. I've set up a mailing list to be used for announcing test versions of apps. Anyone can sign up and post messages, but the only messages posted should be announcements of new test versions of apps for people to test. It's designed to be a low volume list so it's not too disruptive of people's inboxes. Here's the welcome test with the details:
Welcome to the PortableApps.com Beta list. This list is for sending announcements of new Development Test and Pre-Releases of applications in PortableApps.com Format for the beta team to look over. Please send only one message per release to the list and only include a link to the PortableApps.com Forum topic where you announce the release. All followup messages, bug reports, comments and questions should be addressed to the forum topic and not this list. This is a low traffic, announcement-only mailing list.
You can sign up for the list here:
https://lists.sourceforge.net/lists/listinfo/portableapps-beta
Only want Pre-Releases?: If you only want to worry about pre-releases, you can just monitor the 'TEST: Pre-Releases' package on SourceForge.net and you'll get an email whenever a file is posted. All PortableApps.com pre-releases will be posted to SourceForge, so you'll always get a ping as soon as the file is posted.