My computer thinks Java web start applets (.jnlp extensions) are Prism files. Prism doesn't know what to do with them.

We've had a Prism Mac user report that an update to Mac OSX with Java and Safari fails to appropriately recognize .jnlp extensions. When trying to launch Java web start applets OSX defaults to random apps that can recognize xml, such as Prism, TextEdit, etc.  The fix requires manually finding the Java Web Start app in OSX and setting all the .jnlp files to open with Java.