Just upgraded to 2.5 and it was very smooth...however I just noticed a problem. I have a page called Photo Gallery at /wordpress/photo-gallery/ with several sub pages where I have my photos separated by year, ie. /wordpress/photo-gallery/2005/, /wordpress/photo-gallery/2006/, etc. However my subpages that have only #'s in the permalink don't show--they show the immediate parent page instead. But, if I navigate to /wordpress/photo-gallery/2005/2005/ I can get to the page, even though that's not the correct permalink.
This only happens for pages that are all #'s. Pages that start with numbers but have other characters in them work fine. I'm not sure if this is a bug or something got whacked on my .htaccess or what. Any ideas? I'll install a fresh version of 2.5 and see if I can replicate it.
BTW, I'm using NextGen Gallery as my photo gallery, but had the same issues when I created a blank page and titled it "1234." You can check out the phenomenon here. Thanks.