I'm considering using memcached (at some point) in my application i'm currently developing.
Eventually, i'm planning on hosting this on Amazon EC2 - i was just wondering, would it be possible to have a linux server (aws instance) running memcached, and use the windows server (aws instance) for the app, but set it to use the linux server for the cache??
Definitely possible. I suggest using the enyim.com client instead of the "official one" as it a lot faster.
You can access the MemCached service if you use NHibernate NHContrib extension for memcache at http://nhcontrib.wiki.sourceforge.net/