Public key crypto schemes (RSA, elliptic curve etc.) are vulnerable to some variation of Shor's algorithm. We'll have to move to quantum crypto when this happens. Hell for all I know D-Wave's machines can already break RSA for the DHS.

http://www.infosecisland.com/blogview/19707-The-Emerging-Thr...

The 256 bit key size is still the recommended maximum since no increase will help against quantum computers.