The most recent research by Dr. Daniel Klem, who has been studying the problem of bird/window collisions since the 1990s, has just been published in the June 2009 Wilson Bulletin. It is available, along with lots of other bird/window resources, at his website here.
Klem tested the effectiveness of various window treatments confirming, for example, that single decals on a window are not effective at preventing bird collisions, and that the non-reflective Collidescape film is nearly 100% effective at preventing collisions. Several different UV-absorbing films were tested with small to moderate success.
Beginning in 2007 Klem tested a new film developed in collaboration with Dr. Tony Port, a chemist at CPFilms. This film has vertical strips that reflect UV wavelengths alternating with vertical stripes that absorb UV wavelengths. The UV reflection and the alternating pattern seems to be very effective at deterring birds – only a few birds collided with the windows treated with this film, and none of those collisions were fatal. The real promise of this film lies in the fact that it appears clear to humans, and should be relatively easy to apply to existing windows!
Hopefully the company, CPFilms, can be convinced that there is a market for this window film, and start producing it commercially. I can think of dozens of windows that I would put it on.
Klem, Daniel, Jr. 2009. Preventing Bird-Window Collisions. The Wilson Journal of Ornithology 121:314 –321