Themes - 'upgrading season' for WP 2.7

Hello Guys

I do make several themes from the 100 Farm pack available for users. Now that WP 2.7 is out the 'upgrading season' starts. Seems that for some of the new features of WP 2.7 there is a need to add (or change) some code in the themes.

Does anyone are aware of that - any advice?