1 Year from sony is better than the in store as you get the console back insanely fast. Most hardware problems occur in that first year anyway so you don't really need to buy the warranty. If you're home is more high risk (kids/pets) then maybe it would be better to get it, as the cost to repair it is about the price of the warranty.
The PS3 comes with a one year warranty from Sony and some stores have a decent warranty offer, last year when I got my 60 gig from K-Mart it was about $60.00 for an extra two year warranty (it's part of the Sears program).
Having had my PS3 blu-ray drive stop working this weekend, and Sony charge me £99 to fix it, I'd recommend anyone reading this now to get the best value protection plan you can.
I've had my PS3 since UK launch (so about 2.5 years now) and to be fair, it's only just packed up - everything else still works (can play my videos through it etc), but it's less than ideal.
Sure, only people who've had trouble are going to be recommending protection plans like this, so I guess it depends how risk adverse you are as an individual, but when it comes back fixed in a month; I'm buying a 3 year protection plan.