Sorry for the bump, but I guess Google doesn't celebrate Memorial Day either.

I'm also into corporate branding...and I think Google is stepping away from Google Doodles.
If you look at how they're re-branding their websites with a much more serious, uniform look, and how un-serious their doodles are...it's like night and day.
Prime example of re-branding:

to

I also have a different theory for why the doodles have ceased: the economy. Maybe Dennis Hwang was laid off. Who knows? Guess we'll find out soon enough.