Is this project still active?
This bug https://issues.jboss.org/browse/SNOWDROP-57 is pretty critical in that it won't shutdown Spring properly, but I see no activity since a month ago. It's an easy one-line fix ( I even found the line to change and provided in the comment).
I really like the Snowdrop feature in that it integrates Spring so seemlessly with JBossAS. It's kinda sad to see it being stagnant.
At the meantime, for those who is looking for a workaround, you may download a fixed jar here: https://github.com/saltnlight5/snowdrop/downloads
The project is active and the bug you are asking about will be fixed in the 2.0.4 release, by the end of this week or early next.
Thanks for the interest,