BTW - I've used the Fermcap-S stuff in my boils for a while since I have a 7 gallon pot and I'm always boiling right to the top.
With this hyperactive Starr Hill yeast, I dropped some in at the start of fermentation and the krausen never even hit the top of the carboy. I guess I'm a fan.
This is interesting (not my pictures, just something off the web):
http://www.flickr.com/photos/plaztikjezuz/2311342840/in/set-72157604044357632/