Intermittent problem, seemingly dependent on what editor is open when eclipse is closed.
If I have a .jsp open in an editor window (or .xml) and in focus, when restarting eclipse it will hang.
The workaround to this is to delete all the <editor>...</editor> elements and their content from the workbench.xml eclipse file. If I have multiple editors open, sometimes I have the patience to find the one that is causing the problem and just delete that element from the workbench.xml.
When I close Eclipse with a .java file open in an editor and in focus, I do not have this problem.
I have had this problem for months, and was having a bear of a time figuring out what was causing this, and a teammate installed this plugin (at my behest, and later to my embarrassment) and his Eclipse hung when restarting. I cleaned his workbench.xml of open editors and it came up fine. He had installed 1.3, and had an xml file open at the time. I updated my version to 1.3, and can still reproduce the hang by simply closing Eclipse with an open jsp file.
I could probably produce a stack dump while hung if it would help, but I'm not proficient enough with RCP to debug the problem myself.