To 2.5. All this time, I’ve been using 1.5 or some really early version of WordPress. Other blogs I use or manage are more recent, but Yellow Dog has always stayed true to its roots (I used Graymatter for years before finally switching to WordPress during the InsideHigherEd commotion).
2.5 is all flashy, media enabled, extras pushed to the side of the user interface. Post/Write are the upfront options. In the post box, categories, comments, tags, etc are pushed from the sidebar to below. The ride so far feels odd. Doable. But odd.