If you are looking for value in a console, the PS3 is the way to go. Considering it is practically a computer/media center on its own, plus a blu-ray player, its a simple decision, and considering a stand-alone bluray is still in the $350-$400 range, if you go with the 40GB model you're practically getting a blu-ray player with a high-end gaming console built in.
However, that's not to say that the 360 has nothing to offer. It does have a DVD player and up to 1080p output just like the PS3. While HD-DVD did lose the format wars, I would expect a bluray attachment at some point. Xbox Live is easily the leader in online gaming, despite having to pay for the service. Sony and Nintendo both are lagging behind (possibly pun intended) with online gaming when compared to Microsoft.
Final thoughts:
If you are looking long-term for a console, probably go with the PS3. It has a much more powerful processor that has yet to be fully taken advantage of, but once it does expect some incredible games both visually and in gameplay. PS3 online isn't bad, but its got some work to do.
If going short-term, probably look more at a 360. They have a massive game library of games for nearly any gaming type, and playing with/against other people across xbox live only adds to the lives of these games. They should eventually get a blu-ray addition too, so that may be worth the wait as well.
BTW...buy.com has refurb. xbox 360 premiums for $199.99 (last i checked still available). Just throwing that out there.