As I have posted before (see also here), Ubuntu is an alternative to using Gentoo on the Open Client, even though getting the image working using debootstrap might not always be easy.

Using the Ubuntu installer created by Peter Czanic (info here) things have become much easier.
This installer will only work for the bleeding edge Gutsy, so be careful using this in mission critical places :-)

Using Ubuntu instead of Gentoo has the advantage that a system can be up and running faster from scratch, since the tedious compilation is not needed.
However, the performance of the Ubuntu image is notably slower than the highly optimised Gentoo image.

Naturally, you can host both images on the server, and start whatever you want for whatever situation you're in. I use the Ubuntu image for instance to do quick tests and general demonstration, while the Gentoo image is a stable and fast platform to deploy in real implementations after the details have been worked out in the Ubuntu image.

Conclusion: both Gentoo and Ubuntu images complement each other very well!