I've been doing a lot of reading and research around memcached. With the excellent help of a co-worker some interesting work has been completed that I hope to talk more about soon as well. But, along the way I've collected a lot of links and resources about that topic. Here are a few of the more notable ones I thought I'd share.

Distributed Caching with Memcached - This one is a few years old and usually anything over 1-2 years is so dated it's not terribly relevant. But, this article is excellent and a great foundation for getting started with memcached.
http://www.linuxjournal.com/article/7451

Good memcached FAQ - This FAQ is excellent. A lot of good and very useful information in a compact form. Can't beat that!
http://www.socialtext.net/memcached/index.cgi?faq

memcached at Facebook - This is a document about how they use memcached at Facebook. The data here is a little old so I'd sure like to get up to date information but this one stands out because of the sheer scale of what facebook was doing with memcached.
http://lists.danga.com/pipermail/memcached/2007-May/004098.html