UCSB researchers demonstrate that 15=3x5 about half of the time (eurekalert.org)

That's really cool. I didn't realize how hard it is to factor large numbers. Looking at the Wikipedia page on RSA numbers, can you believe this number has not been factored:

12462036678171878406583504460810659043482037465167880575481878 88832896668011882108550360395702725087475098647684384586210548 65537970253930571891217684318286362846948405301614416430468066 875699415246993185704183030512549594371372159029236099