Perhaps a slightly old thread, but figured that I should share my findings as a webdeveloper.
I agree that it'll have to do with your audience, to some degree. At the moment, I'm seing a huge increase in larger widescreen screen resolutions on the web (at least 1280x800). I still stick at optmizing page width for 1024 tho.
And when doing so, I use a max width of 960 pixels, which can be divided into 12 or 16 columns (60 or 40 pixels each with a 20px gutter between columns) , for creating an easy-to-maintain grid.
Example photoshop templates can be found at http://960.gs/
, and for general web-tips I suggest http://www.smashingmagazine.com/