Google released a code search engine to catch up with Krugle, Koders, and Codease.
Like most of the other Google’s tools it can be easily abused for hacking...
I tried this Google code search looking for "BUGBUG", which happens to be a particular string you'll find in comments that Microsoft and IBM programmers often used to mark a known bogosity/vulnerability in the code that wasn't going to be fixed right away. I've used the "BUGBUG" tagging method myself at times.
H/T 1 Raindrop