Whether I buy one or not depends entirely on if they give us system link capabilities like xbox and the games to use it. thats why I never got a ps2, before i got broadband my friends and I eventually got 4 boxes and 4 tvs and would go crazy on halo 1.
kai makes things even better now that we'ved moved farther away and there are a lot more sys link enabled games out there. Their are some really great games that playstation has and will get that I want but w/o the link it's too limited despite all the other features like blu-ray and card readers, hdtv....that i don't care about. Even with xbox live, as popular as it is, sony could take advantage of networks like kai by making their system able to utilize them and push their own network for the MMORPGs.
That way they don't even have to risk investing in a "live" like service that may fail.
That said, 400 for the 360 package or 400-500+ for the ps3 and $60-70 games for either is just not worth it if you already have most multimedia capabilities, maybe if you choose one to build your entertainment center around it might be worth it but from what i've seen using one machine to play games and movies will just wear out the drive faster and you'll need to replace it or just put up with the choppy video play and dirty disc errors. I'll be waiting a year or 2 for them to build up their game libraries and come down in price, unless of course they're modded sooner than that