I logged in and checked out a working version of Liferay 4.2 (see adn register yourself at http://demo.liferay.net) and was, again, very excited at the thought of having most, if not all, the key portlets available to the Histiocytosis community. Its not particularly flashy - just clean and simple functionality and everything you want seems to available when you want it. I especially like the new widget-like thing at the top to help the user navigate and configure the space.
One thing I thought was particularly useful in the Document Library (nice to see one that works!) is that when you search documents it also seems to search the content! I've only actually loaded in a couple of PDFs but even so its already an exciting prospect to have that capability on the site (...I really don't get out much!).