Perlbal as an accelerator for dynamic-but-cachable content

Hi all,

As it is, Perlbal makes a great "accelerator" for application servers.
By buffering and handling connections, it takes a huge amount of work
off the fat and slow backend servers. It's also amazingly good at
serving static content efficiently.

These are totally useful, and help a lot, but why, oh why, does it not cache?

Much of the content that is generated by application servers these
days is dynamic content, but it is frequently highly cachable.

Caching this stuff is a massive gain on busy sites, because with it,
an application server may only have to generate one request for every
10k requests that arrive.

With Perlbal every hit makes it back to the application servers.

What is LiveJournal (or others) doing to serve up these
dynamic-but-cachable requests efficiently? Are they just optimizing
dynamic generation (memcached, etc) so it doesn't hurt so bad, and
buying additional servers?

If I wanted to take try implementing some simple in-memory caching,
what would be a good approach with Perlbal?

Thanks all,
Jake