This compelling little mystery can now be safely put to bed

Inside Google asks:

"Matt Mullenweg (creator of WordPress, the software that powers this blog) says he sees that Google has widened its search box. I'm not sure . What do you guys think?"

Well, the following analysis is the result of my jet lag...

I'd answer a definitive yes - the search box has most certainly widened.  Google in 2005 (minus the grey box, as the Internet Archive doesn't render the orignal Google logo image):

    

Google in May 2005:

So you see, this compelling little mystery can now be safely put to bed. Where I should be.