Don't let the lack of flashing put you off. Like others have said, you can always get another light and mount it to the seatpost or part of the rack (Planet Bike sells mounts that fit the small-diameter tubing on racks).

And, to be honest, they're quite visible lights already. I've seen enough of them on German streets.

I bought an D'Lumotec Oval Plus Senso LED headlight and a Selectra Plus taillight. I'm not sure if the Selectra is available in the States, but it's slick -- it has a standlight and two side LEDs. The main LED is red, too, not washed out like you see in that pic.

The wiring is no big deal, either. The shop gave me a length of wire with plugs on one end, long enough to go from the handlebars (if I wanted; I mounted my headlight on the fork crown), down the downtube, along a chainstay, and up a rack tube. Took less than ten minutes to install, including bolting the light to the rack; maybe 20 minutes total, including the headlight.

So, anyway, I'd say to get a taillight and run it off the dynohub. There's not enough reason not to, and it'll just use free energy.