Linux "Rolling Distributions" always sound like a good idea. You get the latest stable distribution, and then on top of that you get the latest package updates shortly after they are released, rather than having to wait for the next major distribution update. In practice, though, they have often turned out to be a bit problematic. Keeping up with a lot of package updates is tedious and time consuming, and finding a good balance between rolling them into the main distribution quickly and making sure they are stable can be tricky. It is starting to look like openSuSE is doing a good job of this, with their "Tumbleweed" distribution.
Tumbleweed was announced with or shortly after their 11.4 release. I was a bit skeptical at the time, because of my experience with other rolling distributions, but I set up one of my netbooks to track the tumbleweed repositories, and the results have been quite good. Updates come through in very good time, and the overall system stability and reliability don't seem to have suffered. To give just one small example, digiKam (my favorite photo management package) is on release 2.2 in the standard openSuSE distribution (which is still quite good compared to most other major distributions), but it is already up to 2.5 in Tumbleweed.
There is a brief description on the Tumbleweed Portal page, along with instructions on how to change an installed 12.1 (or 11.4) system to the Tumbleweed repositories. The zypper commands can be copied directly from that page and pasted into a root shell to make the conversion. The magnitude of the change is obvious from the number of updates that will be installed - something like 200 packages either new or updated after changing to the Tumbleweed repositories. Of course, it has been a while since the 12.1 release, so this is to be expected.
If you are already an openSuSE user, you probably know about Tumbleweed - but if like me you haven't taken the time to really try it yet, I would advise you to go ahead and do so, it is well worth the effort. If you haven't been using openSuSE, then Tumbleweed might be just enough incentive to get you to try it.