Not really.
The steam is imply a vehicle to carry heat; in giving up the heat, the steam simply condenses to water and drains down along with the heated and less viscous oil and bitumen. There are a few possbile sources of danger: steaming too fast, allowing a pressure build-up (connacher has streesed that they are proceesing slowly to prevent this); another would be if the deposits were too shallow, thus not having a sufficiently thick overburden to hold the steam in place (again, as I understand it, our situation is that the deposit is relatively deep).
Not to deny the possibility of THAI or other new processes' being used at the Great Divide project. I refer you to the following article; I found it quite interesting:
http://www.ntm.nickles.com/issues/story.aspx?aid=1000378964&ref=rss
Ming Sen