It used to really amaze me that some people always knew immediately when there were new updates to software applications -- and this goes back to the old days when many applications weren't self-updating. I always wondered how they knew about these software updates so fast. With today's RSS feeds it's pretty easy.
On the client side, I mostly just use Macs these days, and there are at least two nice sites that provide information on software updates for Mac users, and they both have RSS feeds. The two sites I follow are VersionTracker and MacUpdate. You can find their RSS feed links on their sites, or you can find the links I use here:
While I'm in the neighborhood, if you don't currently use an RSS reader, I've been using NetNewsWire lately, and I've been pretty happy with it. At some point I'll probably switch to using NewsGator Online or another online service so I can keep all my feeds in one place, but I haven't taken the time to do so yet.
Apple/Mac major news sites
Okay, since I seem to have drifted into the neighborhood of Apple and Mac OS X news updates, here are links to other major Apple/Mac news sites that I subscribe to:
Finally, if a zillion links on one page won't immediately throw you into a seizure, there's mac.alltop.com, an online aggregator of news feeds for people that don't have a news reader.