Afternoon Ivan:
What is a good time of day to help you via IRC or Skype?
The Eclipse "OSGi" runtime is very careful about compatibility and configuration when starting up. In this case either the forms jar was not available, or it did not match the expected version and was thus not loaded. This step you are stuck on is the most maddening thing about Eclipse RCP, often you can get things running from within Eclipse, and then export and be stuck back here at startup issues.
The steps I do to check what is missing, and why, are to go to the run configuration (which was generated when you clicked "run" on the udig.product file).
This dialog has 4 tabs, the one we are interested in is the *Plugins* tab, and the **Validate Plugins** button. This button performs the same checks that are preformed when the application starts up, and more importantly gives you a relatively easy tree, showing what plugin prevented which other plugin from starting.
The other button of interest is **Add Required Plugins** that can act as a band aid, allowing you to launch, even if the application did not list everything it needed to start up.
I apologise for this slow start :( We have been messing with our dependencies in order to migrate from jars to plugins a bit more.