There's a stable version, a beta version, and a 'dev' version.
As with any product, non-tech oriented users that want to begin implementing the product should use the stable version which is updated frequently.
The beta channel is just what the term implies. It's aimed at those the want a peek at what may be coming and comment on how the features work with their systems.
Finally, the 'dev' version is mostly aimed at developers. Those building extensions or otherwise contributing to Chrome via the Chromium project.
Earlier today, the 'dev' version was updated to version 5.0.335.0. The release notes can be found here.
After reading numerous comments earlier today I thought it was important to point something out.
In early versions of Chrome, it was easy to switch back and forth using a 'channel changer' program. For best results, now that the product is maturing, you are MUCH better off uninstalling your previous channel version before changing to a different channel. (Updates within the same channel will still be as easy as hitting 'about').
For those experiencing tab crashes or other issues, I hope this brief piece helps. More details on the various Early Release Channels of Chrome can be found here.