Ubuntu 13.10's release notes mention that it includes Linux 3.11, which supports something called zswap:
Zswap is a lightweight, write-behind compressed cache for swap pages. It takes pages that are in the process of being swapped out and attempts to compress them into a dynamically allocated RAM-based memory pool. If this process is successful, the writeback to the swap device is deferred and, in many cases, avoided completely. This results in a significant I/O reduction and performance gains for systems that are swapping
That sounds cool. How can I try it out?