In Eclipse, I can format comments by selecting them and pressing Shift + Ctrl + F. For example, when I select a method comment like this:
Shift + Ctrl + F
/** *
The closest thing that you can get is Edit | Join Lines (Ctrl+Shift+J). You have to select the lines you want to join first.
Edit
Join Lines
To wrap long comments enable Settings | Code Style | JavaDoc | Wrap at right margin.
Settings
Code Style
JavaDoc
Wrap at right margin