There is a concept of it in the SW side of things. Not so sure about the FW side.
For SW tanks LEDs tend towards the bluer-side, which a lot of people think grows less algae (although this doesn't really apply to cyano). Many people on the saltie-side think that bulbs in the lower kelvin range will encourage algae growth. I'm not sure how true this is since I encourage algae growth, rather then prevent it. :laugh:
I see no reason for this to be true of the FW side though. For one, FW plants like the same spectrum as algae. Any LED light you design to grow plants would grow algae also.
Nothing really wrong with LED's for planted tanks. There is just no reason to spend the money on the traditional setups though. But some of the cheap experimental systems that people are playing with on some of the marine forums (like LED track lighting) could work quite nicely for planted tanks.