UPDATE (9/21/09):
It took us a week longer to finish getting the closet framed than we expected but now it is done! Getting the framing done was actually quite simple. The hold-up was getting a bunch of prep work done around the closet framing, like placing studs for the upcoming sheetrock job (which we are NOT doing!). Here are before pictures (post-demo) and after pictures (taken this morning). We think the room is ready for sheetrockers now and we're hoping to get that part done in the next couple of weeks. We have a another window and a door to install, then the floor (woodlike snap-together laminate) and trim work will be next. When this is all done, I might like it so much that it might become the master bedroom instead of the guest bedroom!