Talking about Ubuntu, the new version - 9.10 Karmic Koala - has just been officially released !
For those who want to give it a try : http://www.ubuntu.com/
If you can use Bittorrent, use it, in order to relieve the servers. Otherwise (limited bandwidth, speed limitation on p2p traffic), you can take the direct download. But I suggest to wait at least a week because the servers are currently almost saturated.
On my side, I won't upgrade, I'll wait until Lucid Lynx is released and for this, I configured my update manager so it will watch only LTS versions. But I'll download the iso and burn it anyway, and probably live-test lubuntu (the new variant with lxde environment which is even more lightweight than xfce).
Needless to say that this year is a major year in terms of OS releases : Snow Leopard, a few months ago, then Seven this month, then Ubuntu 9.10 today.