http://jesterscourt.cc/2013/04/23/boston-marathon-bombing-just-a-hunch/
Terrorist #1 Amazon.com wishlist (from Jester) (FR thread)
Tamerlan Amazon wish list (the Amazon page)
I'm gonna go out on a limb and assume it didn't take a court order for Twitter user Jester to find it.
It's hard to call the FBI vetting "thorough" after looking at that and seeing his interests going back to 2006.