if you zoom into London on google maps – the streetview button appears!

however, it doesnt appear to do anything at moment.

my guess is that this is a precursor to a Streetview London launch.

interesting.

its gone now.

darn. wish i had grabbed a screenshot.

Hmm i have a streetview option to, but there are no streetview pictures availible. Maybe it is activated by the streetview option of France.

the button appears over germany too for some weeks

Yeah, I also noticed it over Stuttgart, Germany, recently but clicking it didn't result in anything.

I'm seeing the button here (US) too over Germany. I couldn't see the button over London though.