I thought about it and to me it doesn't make a difference since I don't have the technical know-how to execute it.
That is, if it's easy enough to do and people want it, a developer can do it and I wouldn't mind.
It would look more apple like but I also wanted MR to keep its own feel so that it doesn't just come off as some fanboy site obsessed with Aqua/Mac OS X
Then you should remove the rounded left part. Just make it a input box and put a "Search" button next to it. The regular, OS-defined widget button, just like how it is right now.
Simplification of code for the win. And one less image to load!