I have the Dremel tool drum sander mandrel on the left. I don't think the design has changed since 1962, and it sucks mightily. Sanding drums get stuck on it and new ones don't fit on it (at least not for me). I just read Stuart Deutsch's post on Make about the EZ Drum Sanding Mandrel, which sounds like a game-changing improvement on the black rubber mandrel.
Dremel has introduced a couple of new “EZ Lock” rotary tool accessories in recent years that allow for tool-free bit/disc/pad changes. The newest EZ-change addition, a sanding mandrel, has quickly become one of my favorites. With the old-style sanding mandrel, you must toil with a small screw before and after swapping in a fresh sanding sleeve, but with this one you just push and pull.
I have been quite pleased with the direction Dremel has been headed. They dominate the rotary tool and accessories market, so they don’t really need to upgrade little things like mandrels, but they have been doing it anyways. Recent models, such as the 3000 and updated 4000 series rotary tools, feature a built-on collet wrench, and it looks like the upcoming Dremel 4200 will feature a new completely tool-free collet-lock mechanism.