Honestly, I dunno who's in better shape... MS has the install base and software sales, but H3 is spent now, and while there's some Epic games in the future, nothing has the impact that Halo does these days...
Sony on the other hand, is suffering from lowest install base, and a lot of negative media... I mean, the prices could turn it around, and they have a nice future for AAA titles starting this month and into next year which includes MGS4, KZ2, GT, and maybe something with FF in the title... So who knows...
Just the only thing that's going to stop the Wii is Ninty themselves, as in their future of games, and to another degree, the quality of 3rd party titles... When will the honeymoon end? I dunno, not through the end of this year though...