This.
Even if Microsoft dropped the price of the 360 to, like, $50*, I'm still not buying one, because A) I can still play NHL and FIFA and GTA offline while PSN is down, it's not like the games are worthless, and B) once PSN is back it will continue to be free whereas I would have to subscribe to XBox Live, and C) I'd have to go out and buy a whole bunch of new games in addition to the nominal cost of the system. This is a major pain, sure, but be realistic: it's a temporary loss of a portion of the system's utility. And, I might add, a portion of the utility that Sony is offering for free while their biggest competitor charges for substantially the same service. Right now for my $0 I get no PSN, but if I had a 360, for $0 I'd get no XBox Live either.
(The timing of the outage is also reasonably convenient, from my personal standpoint anyway, in that it's May so there's a ton of good TV on most nights, plus NHL playoffs, plus baseball; if this had happened in July, I'd have a lot more spare time on a given weeknight that I'd be looking to fill by playing the PS3.)
(On the other hand, I write this as someone who grew up in the 1980s playing an NES, and for most of my life I've been playing video games without any online component; if I were 16 and I had no concept in my mind of a console that didn't support online play, I would imagine this would be a bigger issue for me.)
* I was going to say $0, but obviously if it were free I'd take the system just to have the option to buy other stuff for it in the future.