I've held off purchasing for 3 months whilst waiting for this new round of MBPs. Only interested in 13", and over the past generation I've liked the Air's body shape better. I still do, and I can't really believe it but I think I'm about to purchase an Air over the newest Macbook Pro... yeah, that one I've been waiting for for 3 months.
My reasoning
1) I don't have much need for the full strength processor of the MBP. Even with Lightroom and Photoshop most people report no trouble (I have no interested in gaming on this machine)
2) The Air's battery life is only several hours more, but those several hours put it in a whole different usability level once you factor in battery wear over a year or two, and the realities of a '9 hour battery' not quite giving enough confidence to leave the charger home on an overnight trip
3) The body of the Air, while larger, is easier to hold and easier and more comfortable) to type on. Even more, the perceived lightness is a big factor for me - even if the Air and Pro were the same weight I suspect I (and many) would judge the Air to be much lighter. That's not a factor when in a bag --although half a pound is, but strangely not a consideration for me-- but I can't discount that feeling when in use.
4) This one is completely illogical, or at least mostly so... I feel better getting a 4gb Air than I do the 4gb MBP. There's the resale argument another poster made in this thread, which I think is a great point. But even more it just feels wrong to get a 4gb Pro, even though it'd probably do me just fine. I will be using parallels, or possibly straight up Windows 7 in bootcamp to run some enterprise type windows only apps (e.g. IE, Sharepoint designer, but no Visual Studio). But the cost savings of a refurb or even new 4gb MBA, compared to the cost of a 8gb MBP are considerable. There is a real risk I will run short with only 4gb of RAM, but when I factor in the great swap speed I see many people comment on with the new SSDs (when 4gb of RAM proves to be too little) the ~$400 difference in cost seems worth the gamble (ammirite on that $400?).
But *sigh,* the significant screen real estate of the Retina display I'd be giving up is holding me back. IPS is valuable to me for photo editing (nothing professional) and viewing angle, but that setting on the Pro that uses all of the pixels is the truly attractive feature, at least for those of us lucky enough to have good enough eyes to read two documents side-by-side on a 13" screen.