I have done some work on code search that's different from krugle, google code search, etc.:

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=972749

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1007979

http://portal.acm.org/citation.cfm?id=776816.776831

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1357819