tools for notification of new software revision

Question

I'm wondering if there are any projects out there to create a standard for subscribing to notification of software updates in a way that can be easily aggregated (e.g. RSS feeds?), so that it's easy to check dozens or hundreds of software projects I'm interested in for new releases.

[edit: moved the other half of the question that was formerly here]

Answer 1

Appcasts are one option which are used by tools like Sparkle and AppFresh. There's also PAD, which tends more towards application description than a feed of updates.