It is possible to make dimmable fluorescent lamps by separating the
control gear from the tubes. One can see this with larger fittings,
but this has been difficult to reproduce with a small lamp that has
the control gear and tube integrated in one unit.

We had dimmable fluorescents in the lecture theatres at university, back in the
early 80s. It's not like it is a new technology, but you are right about it
being more difficult to handle over just two wires, when the control gear is in
the lamp fitting. I think the ultimate solution would be sending signal and
power separately to the bulbs, i.e. full power piggy-backed with a signal to
tell the bulb what brightness to set itself to. It would work kind of like those
X11 home automation systems, with the receivers built into the bulbs.

-- JJ