Rob and James have published a great introduction to Apache Camel named SOA Made Easy with Open Source Apache Camel. This is a very light intro but it serves as a good example of how really easy Camel is to understand but how really powerful it can be. Digging into Camel is really quite easy and a lot of fun. In a short amount of time you will be easily routing messages between endpoints. Camel offers integration into a wide range of technologies using Camel URIs. For more information, see the Camel website.
A word of warning: This article is published at SysCon whose website I can hardly bear to open because of all cruft. Luckily I run a hosts file full of URLs for known advertisers that I route to a dead end so I don't see many ads.