This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
I had two issues when trying to do the same. The first was the provider complaining that I didn't have a usable context. I fixed this by explicitly creating a JndiTemplate and configuring it with the usual JNDI context stuff. (Maybe because I'm running Weblogic at port 7011???)
At this point, I started getting the same error you did. On a long shot, I dropped the resource-ref param so that JndiObjectFactoryBean wouldn't supplement my jndiName with "java:comp/env/", since I don't supply this myself when manually getting a datasource. It worked. In the end, my key beans looks like this: