http://news.yahoo.com/s/pcworld/20060707/tc_pcworld/126371

Though Google is widely used to search the Internet for Web pages and office documents, the search engine can also peek through the binary information stored in the normally unreadable executable (.exe) files that are run by Windows computers. "They actually look inside the internals of an executable and index that information," Hubbard said

There's an interesting insite at the end of the article

<quote>
The most interesting thing about Google's binary search capability is not its security implications, Long said, but the fact that it shows that Google may be thinking about becoming a file searching service.

"There is this whole wealth of files out there that Google's not touching," he said. "This indicates that they're spreading out into more avenues and that they're probably going to be crawling more content than what they're looking at now."
</quote>

"thinking about becoming a file searching service" is a little late for me :D