ultracache is based upon the assumption that network I/O will saturate before your memory or CPU. 

This is all a work in progress but the idea is that an efficient UDP protocol will let you harness more of your cache servers for large installations.

The difference between ultracache and memcached ends here, beyond this they have the same API and are just as capable, well memcached being a slightly bit more capable at the moment.

It current pushes 150.000 GET operations per second, meaning a 300.000 packet per second throughput.
While the CPU isn't fully saturated it appears as if network I/O is indeed the limiting factor. 

Feel free to contribute!