In my earlier post I neglected to note that the subversion revision of OpenOCD I used to first test the SDRAM initialization script on my PXA255 target was version 281. I tried the latest from SVN today (version 291) and things are still operational. If you plan to do anything with flash memory on a PXA255 target you really need to get the target’s SDRAM initialized properly in order to make OpenOCD useable, at least with the Olimex USB and USB TINY JTAG devices.
You need to keep track of subversion revisions when playing with OpenOCD as the pace of development at present (early 2008) is fast and furious, and things can occasionally break. If you discover a revision that works for you, it’s best to stick with it until you have a real need to upgrade.