The latest version is 2.1. This is largely a bug-fix release to 2.0. The previous version is 1.3.x. I don't have much information on other distributions. Here is what I have gathered from various sources.
Caldera is an rpm based distribution.
It is particularly targeted for Novell Netware users. It has some GUI tools. S.E. is gaining popularity. It bundles a lot tools and utilities. It largely boils down to personal preferences.