Google Code Search is now live. I am not much of a code searcher but this is how code.google.com the site for external developers interested in Google-related development, free source code and API services explains the new Google Code Search
Google Code Search Offers:
*programmers a single place to search publicly accessible source code.
*support for precise searches using regular expressions
*restricts code search by language, license, or filename with advanced operators
* a search index that includes billions of lines of code
Source: Googling Google