What people often don't mention, when it comes to the price of the PS3 vs. the 360, $100 more for the PS3 gets you wireless Internet (no special adapter needed), blu-ray playback, and unlimited online play... purchased separately, that alone is worth more than $399! Sony just needs to do a better job of getting that message across, and, oh yeah, the games.
If you don't need those things then it's not a selling point. My best friend is in the market for a new system, but he doesn't care about wireless gaming, or even internet gaming in general, nor does he care about Blu Ray. I can't even sell him on the idea that his big PS2 library of games would at least work, because the PS3 doesn't even have that!
Sony's problem is that they only way they can sell their GAMING system is by hyping all their features that have little to nothing to do with actual GAMING. They try and push stuff like Blu Ray and PSN Home and the like, but if all you want to do is sit down and play games, there are very few compelling reasons to pick a PS3 over a 360.
I own all 3 systems, and my 360 gets much more usage overall than the other 2 combined (unless you count playing "Eternal Darkness" on the GC-enabled Wii, which makes it a bit more even.) My PS3 gets more usage as a video player than it does a game machine, but that's because I put movies on my thumbdrive and then play them on the PS3 on my 50" plasma or 30" CRT. Yes, it is a great feature, but it doesn't do anything to bolster the GAMING aspect of my machine.
Strip every non-game feature, and you essentially have a $200 gaming machine versus a $400 gaming machine of nearly equal audio/video quality. Also consider that the cheaper gaming machine has a much bigger game library than the $400 gaming machine. As an ENTERTAINMENT machine, the PS3 may be a better value out of the box, but as a GAMING machine, the 360 wins hands down.