Hi Doug,
I did have occasion to do a time lapse shadows thrown by trees in a landscape one time, but I had to resort to 3DS trees for it to work. TheTFP photoboard trees cast a shadow but from overhead the trees are just a thin line so looked rediculous and could not be used unfortunately.
They work OK of course from ground or eye level and I have done the same exercise as you mentioned, of sun through windows and size of eaves and also shadows from trees to shade windows. There are several examples of animations like that in the web application that these GIFs were done for. (
www.synergy.net.au/renovator)
In the one with the trees at the front of the house (either), I actually used 3DS trees behind the photoboard ones (which were photos from our garden) as they rounded out the shadows better.
Incidentally, the main rotation movies for the Flash application took 6 hours each to generate! Very frustrating to get to the end (next morning) and find you had left some thing turned off that shoould have been on - did that a few times!!!
Allan.