At time of writing, Netbeans 6.5 is the latest edition.
After downloading from netbeans.org, the barebones
edition i.e. the Netbeans 6.5 SE, it does not come with
JWTK 2.5.2. You will need to add it as a Platform
by clicking on the Tools menu, then Java Platform,
then add Java Platform.
But before you can do that, you will need to install
a plugin first. Goto Tools, then Plugins, then add the
mobility plugin. It's around 9 MB to download.
After intsalling that, then only add the JWTK Platform.
Two other optional plugins are the mobility vmd and
mobility end-to-end.
moility vmd enables you to design the midlet's
GUI visually and also has flow layout view.