Hi,
From your experience, 1680x1050 in 15" is a welcome upgrade for everyone or users that not really need that (photoshop users and such) will find it annoying and too small for this size?
I mentioned this in another thread, but I'll say it again.
In the lab at school they have older Apple Cinema Displays (the kind of with two feet on both ends and the thick clear plastic). I find it easier to work on website mockups in Photoshop on the ACD than on my 15" 1440x900 early 2008 MBP. It gives me just enough more room to have all my toolbars in better configuration, with more breathing room for whatever I'm making. It's not a huge improvement, but for me it was worth the money.
I'm stuck with a 1440x900, so I'm trying to convince myself it's better, or at least tolerable. I use Chrome, and if you go into tools and change zoom to 83% (one click down), it'll save it for that website. So any site that doesn't fit, just zoom it out, and it's set every time you go back.