Hugh Thompson (http://en.wikipedia.org/wiki/Herbert_Hugh_Thompson), a world-renowned expert in application security gave a keynote at GTAC (Google Test Automation Conference). An attendee asked him about Bitcoin. He not only gave a good recommendation, but said he would use bitcoin.

The entire keynote address is entertaining and informative. If you just want to hear his comments on bitcoin go to 1:03:00 into the keynote.

http://www.youtube.com/watch?v=onpxOG3TrWg