Update: There's a fix posted over at Blogger Buzz. (There is now a setting to turn off the code and it's explained over at Buzz.)
The launch of Blogger Images required a bit of new code that is causing some users annoying layout problems. Before launch, the templates passed our tests but because of the open nature of Blogger templates, we weren't sure which kinds of template modifications were going to be affected. We're hammering out the solution now and we'll update our help site with some workarounds today.