WebKit crashed as I moved the window to the top of the screen.
Created attachment 19154 [details] Problem Report for WebKit Crash log from issue.
I should also mention that this happened while I was on Google Reader.
Created attachment 19163 [details] Problem Report for WebKit Just had the same issue while closing a tab containing Microsoft.com Order Status site.
*** This bug has been marked as a duplicate of 17057 ***