The release that you will be testing is currently not available yet—if you join the mailing list, you'll get an e-mail announcing the new update. Then you'll be able to install the beta update to the module development functionality via the Update Center wizard. If you want to know what the update module will provide, either install the update module, when it becomes available, and take a look at the "What's New in 5.0 Update 1?" topic, or have a look at it here.
Finally, if you read Origami and NetBeans IDE 5.0 a few weeks ago, you might be wondering where the promised code is. Well, if you go to my Update Center (http://blogs.sun.com/roller/resources/geertjan/updates_geertjan.xml), you'll find a new module available:
Note that this new module is the only one in my update center that will work in 5.0. All the other ones have module dependencies that are not satisfied by the 5.0 release; for this reason, I need to rebuild all the other modules (soon) so that they work for 5.0. However, the code folding module should work for you in 5.0 (I tested this out on a fresh 5.0 installation).