I've added her idea to my future ideas bookmarks :) and finally have a good use for the free glass shelves I picked up off craiglist.org a few weeks ago.
Update! Sept. 2nd, 2012:I finally figured out how to do something close enough to the DIY Glass Window Shelves I saw when I originally made this post. Here they are:
Even though most of the shelves get good sun exposure through the window, I was a little concerned about the top shelf. (So much for thinking ahead.) So I added a little plant light on the very top corner of the wall where it meets the ceiling. It looks a little cheesy right now but I think after some plants get growing on these shelves it won't look so bad.
I used these free glass shelves that I had picked up from a local woman who had listed them for free on craiglist.org:
I still have plenty of glass left so I'm still thinking of ways to use up the rest of the stack.
The glass shelves came with cheesy fragile plastic connectors that didn't seem strong enough to hold anything securely, so I used some thumbtacks instead. Yep, I'm that cheap, but after trying it out I discovered cheapness pays off. The glass shelves aren't going to fly off the wood any time soon :)
I just used some 1 1/2" x 3/4" wood also found free in a shed that someone on craigslist.org had to have empty before they moved. The little pieces of wood were really easy to work with (soft) and get the thumbtacks into. They were also strong enough to hold the glass shelves across the 53" span without bending :) I'm thinking of keeping my eyes open for more wood of this small size. It was a nice surprise it worked so well.