I've been looking at my analytics "screen resolutions" page recently and only 5% of my site visitors are at 1024x768. By far the most common screen resolutions are 1280x800 (25%), 1440x900 (15%), and 1680x1050 (10%).
With that in mind, should devs continue to optimize their sites for 1024x768?
You should stop using bogus web statistics based on screen resolution, because a screen resolution of a given size does not imply a browser window of a given size.
Computer displays are getting bigger. That means my efficiency should increase as my ability to manage more things on the screen should increase. I should now be able to do things such as writing a paper with multiple pages from other sources visible at the side for things like citations, and cross-referencing multiple visible documents without having to resort to toggling between windows.
I'd suggest that since so many screens now have a horizontal resolution of 1280 pixels, if you are going to optimize your pages, you should make sure they're optimized for browser windows sized to 640 pixels wide. I'm completely serious.
As a side note, there are multiple reasons why books are printed at the sizes they are. One of the big ones is that with columns of text at the sizes afforded by typical book sizes, humans read with some of the best efficiency.
~70 ems seems to be the consensus for optimal column width. Consider that 70 ems is smaller than a terminal window. I feel bad when I see people at the library open their browsers and maximize them on the Windows machines with 1680 by 1050 displays there, because they got accustomed to maximizing their application windows through conditioning at a time when most displays were 1024 by 768 or smaller. If you're reading Wikipedia on a fullscreen window at 1680 pixels of horizontal resolution, you're only degrading your own reading efficiency, whether you've realized it or not.