I have made an application in Google app engine that is using Beautiful Soup. I\'m using the latest version of it, http://www.crummy.com/software/BeautifulSoup/bs4/download/
BeautifulSoup 4 needs Python 2.7 or newer, but Appengine has Python 2.5 by default. You can either:
Use Python 2.7 on Appengine (Edit: doesn't require a paid app. Thanks Grewe.)
Use BeautifulSoup 3 for now.