[karolist]

It's a fat white border around the image. A variation of this often imitates a photo stack each having such frame.

Google images keywords: polaroid frame, polaroid stack.

Sample: http://blog.simplyjean.com/wp-content/uploads/2007/11/polaro...

What's interesting that this wouldn't be allowed, I think there's many apps using this framing style in the app store already.

[xsmasher]

I assume that Polaroid has asserted some kind of trademark over the Polaroid-style frame, but I couldn't find any such case on Google.