Yes indeed, and actually if you go to the PsychCentral blog yesterday's Friday Flashback post has a link to an older post that has a ton of good info in the comments too. (I would give you the link but I haven't been a forum member long enough to post links yet, sorry.)

Most of the research so far has been for SAD, unipolar depression, and insomnia. A couple of good review articles:

The Efficacy of Light Therapy in the Treatment of Mood Disorders: A Review and Meta-Analysis of the Evidence, Golden et al., Am J Psychiatry 162:656-662, April 2005

Tuunainen A, Kripke DF, Endo T. Light therapy for non-seasonal depression. Cochrane Database of Systematic Reviews 2004, Issue 2. Art. No.: CD004050. DOI: 10.1002/14651858.CD004050.pub2

It is being tested more for bipolar now, and dark therapy is looking intriguing too. The main problem with phototherapy as a bipolar treatment seems to be that it can trigger mania, just like every other treatment for depression.