One of the few things I needed to mess around with to get working when I upgraded from Snow Leopard to Lion was Netbeans.
Very basically Lion doesn't ship with Java, and Netbeans obviously needs Java installed to work.
You would have thought this would have been a simple case of just going onto the Java website and grabbing a download link, but unfortunately they haven't updated their downloads and for OS X it just says to get it from your OS (which was true up until Lion).
Instead the page you should visit is a download for Java hosted on the apple site.
Download the .dmg file, run it, then try and open up Netbeans, it should just automatically work.
Jobs a goodun'