Now's not the time to invest. I'm convinced e-cigs have huge potential and, in the fullness of time, many people will make a lot of money off them. That time will come, but it is not now.
The e-cig world is kind of like the computer business of the early '80s. At that point, everybody knew computers were going to get pretty big and every investor wanted in. And a lot of people made fortunes off of relatively small investments. Many more investors watched their money disappear.... "I really thought the Coleco Adam was going to be a winner." "The Mattel Intellivision/Aquarius... you know a company like that is going to make it." "Atari is making zillions... it can't do anything but get better."
Of course, the opposite is true... I think it was the movie "Forrest Gump" where Gump narrates something like, "My friend had an idea to invest a few dollars in an orchard or something..." and the movie shows him opening mail from Apple computer. [Edit: actually the phrase was ''some kind of fruit company," and, as many pointed out at the time the movie was made, early investors in Apple didn't do very well... although now in 2011, they seem to have made out okay.]
My point again... people are going to make serious money from e-cigs. Many more are going to lose.