I'm not sure quite how to state how awesome Gnome 2.6 is.
It just has a lovely feel to it. Things feel snappier, more polished. The interface is so clean (although so was Gnome 2.4) and things work really well.
Nautilus is so fast... is it really Nautilus? I think they kidnapped Nautilus and put his physically superior twin brother in there.
GStreamer just worked. (No configuration craziness!)
In other awesome news, what is sure to be an open source darling for years to come got an update today: The Battle for Wesnoth
Warning: don't follow that link if you value your productivity for the next week or two. And don't install the addictive Solarwolf either, another excellent open source game. In fact, there are so many great open source games; we should appreciate them more... Freeciv, Vegastrike, Boson, Stratagus (formerly Freecraft), Freecnc, Simutrans (not open source, but fun nonetheless), Pingus, Trackballs, Neverball, and many more.