Shit is very touchy to grow (I thought about it myself, but I can't handle the hassle), powdered is about half as potent and a lot more convenient if you haven't tried it:
http://www.lifesvigor.com/shopexd.asp?id=3921
KB, probably the greatest benefit to wheat grass juice is that it is an extremely potent source of natural chlorophyll, making it a very potent antioxidant and natural detoxifier.
The fresh stuff is amazing though, an incredibly powerful detoxifier.