Since this thread began in January, I continued developing these flexible printer plates. My business is now called http://printinz.com and I will be offering plates to fit the UM2 in June. The latest design is slightly thinner, flatter and much more thermally stable. I solved the warping issues from earlier by making some material changes.
I sent one to a user (chrisp) on this forum so I could make sure it was sized correctly and determine how best to attach it. You can see one of his posts about it http://umforum.ultimaker.com/index.php?/topic/5737-print-plaabs-without-heated-bed/?hl=www.printinz.com. He has more images of things he printed on it http://umforum.ultimaker.com/index.php?/topic/467-post-your-latest-print/page-96?hl=www.printinz.com#entry52127. Turns out it fits perfectly in place of the glass.
You can check out a large PLA print someone did this past week on a MakerBot machine on my https://www.facebook.com/printinz?ref=bookmarks.
Most people are skeptical about these plates until they give one a try... then they love them. They just make printing easier. There are so many variables to contend with to get that first layer to stick just right. My experience is that these plates are just more forgiving and it mitigates some of the sensitivity of the other variables.
Check them out and please let me know if you have any questions. I'm always trying to make them better.