It would be easier to explain I think.
I got the idea while watching a vinyl record spin. Basically, that optical illusion you get when you see what appears to be a constant supply of new grooves disappering into the center of a record. So imagine the 'Rotation' aspect of it simply being the record. The interesting part, the major difference, is that there's basically a play-head for each turn of the spiral, unlike a turntable where the play-head is a single stylus playing only one groove at a time.
So draw a virtual line from the center of the record, to the outer edge. Add a stylus for each groove in the record and place them all on that virtual line. Start playing and the sound you get is the result of every stylus (play-head) sounding at once. In other words, the density of this oscillator would be immense, completely dependent upon the amount of turns in the spiral.
And what about the grooves of the oscillator? Well, just like a record, they can contain anything you like. A sawtooth, square, noise, a voice, anything you like could be formed along the length of the spiral. But the characteristic sound it would produce would be based completely on the fact that it's a 'rotating' oscillator because the sound it outputs is the sum of every play-head the oscillator has. And remember, the amount of play-heads it has is completely dependent upon how dense the spiral is (how many spiral turns you specify using a density knob or whatever).
So that's the basis of the Rotation Oscillator itself.
As for the synthesis side of it, creating an actual Rotation Synthesis synthesizer, well there's some very different parameters for that. Density, as was explained, would control the amount of turns in the spiral and therefore the amount of play-heads making up the output of the oscillator. Speed, which unlike a standard synthesizer, does not control the speed of linear movement of a play-head over time, instead, it controls the speed the spiral is rotating, which is how you control the pitch of the oscillator. Then you would have more conventional stuff like, say, specifying a saw wave be used along the length of the spiral, anything really.
The difference between a standard saw oscillator and a Rotation Oscillator containing a saw, is that the standard oscillator runs in a linear fashion, letting you hear the single saw as the head passes over it. The Rotation Oscillator is quite different in that it's not based on a linear travel, its based on outputting the sum of every head of the spiral in a constantly revolving, ever decreasing and constantly regenerating process.
Other interesting parameters for the Rotating Oscillator are things that controll the density at various stages throughout the length of the spiral. Think of those springs where they have tight winding for the start and end of the spring, but the center part is a lot less dense. Well in a Rotating Oscillator, due to it being based on rotation, editing such things as that would have a massive impact on the sum that is output. Not only because of the changes in density, but also because what is lying directly beneath the play-head of each spiral turn, would change in time due to changes in the density of the spiral along it's length.
If you're thinking about this the way I'm thinking about it, then mind-blowingly dense trance leads would be a peice of cake for a Rotating Oscillator. A rotating oscillator, by it's very nature, has the ability to create dense, thick, lush, all that sort of stuff.
Now one last thing about the Rotating Oscillator is, due to it rotating, I can imagine the density specified by the amount of turns will also effect pitch to an extent. In other words, the more dense the oscillator gets, the lower the overall pitch will sound. Simply up the speed of rotation to counteract this effect, and you're done!
- Earth-rumbling bass strong enough to rattle your nannas false teeth out!
- Trance leads so dense they make you cry with emotion!
- Pads so silky they turn silk-worms green with envy!
Axoman - Ambitious even if slightly off his rocker! 
