Last year showed Busch & Müller
Licht24 , the daytime running lights for bicycles. 2011 follows to fit the ideal security complement for taillights: BrakeTec, the "brake light" on the bike.
At the core of the new technology is BrakeTec into the rear light
integrated processor that evaluates the signals from the hub dynamo. Once the speed drops suddenly and significantly, the rear light shines much brighter.
From B&M's site. So we have hub dynamos specifically mentioned, and a processor that evaluates the signals, which I take to mean the AC frequency.