From Ubuntu 10.10 (Maverick Meerkat), Shotwell is the new default photo manager. I tried it under Ubuntu 10.04 (Lucid Lynx) but the latest version was not available in the standard repositories.
To install the latest version on Lucid, add the Shotwell PPA:
sudo add-apt-repository ppa:shotwell/ppa
sudo apt-get update
sudo apt-get install shotwell
Give it a try and see if it suits your needs!