Not sure about that but there are ways to dim them if you want. Here is an interesting driver.
http://www.leddynamics.com/LuxDrive/datasheets/3021-BuckPuck.pdf
I've got one that I'm going to use with some one watt LED's that I got off ebay. Mine are Luxeon, and lambertian which means 140 degree angle.
They were like $2 ea nd they list for over $5. I'm using them for house lighting scattered all over the place most likely. Wood pile, garage, porch, all 4 corners of the house, etc...
Just don't want the house to look like a space ship.
I'll let you know how it goes.