memcached debate

[andrew at flypublishing.com]

Sorry if this is a well covered topic, new to the list, but my
question is with network latency and memcached.

Could I store say 5 billion items in the cache over say 20 machines,
each with 16 GB of ram, each item keyed off a 64 bit integer?

The value of each item would be a small list of other integers.

Would it be possible to then use this distributed memory cache as if
it were internal memory and access each key many many times.  Say,
like 500 key hits every second.  Or, would network latency make this
impractical?

If we had gig-a-bit connections between all the machines and a really
nice switch, etc.

Thanks.