Looks like Gmail is jumping on the recent Google design changes:
New Gmail header
Old Gmail header
These changes are actually pretty significant and its happening all over Google. And based on what I’ve read about how Google used to operate its design methods I find these changes both refreshing and fascinating, see:
I had a recent debate over whether a border should be 3, 4 or 5 pixels wide, and was asked to prove my case. I can’t operate in an environment like that. I’ve grown tired of debating such minuscule design decisions. There are more exciting design problems in this world to tackle.
Douglas Bowman on Leaving Google, March 2009