Funnily enough, the WWW used to only run on people's "dedicated servers".. now, it's taboo.. how funny.
Anywho, as far as web-based exploits, I distinctly recall reading a story on this very site about someone going into an Apple Store and jailbreaking a few iPhones and iPod touches with the jailbreakme.com web-based exploit.
In short, If they are legit, there is nothing wrong with a web-based JB. Worked then, and if it works now, even better.
All I will say is this.. If this gets released tonight and it indeed works, one person's credibility is going to skyrocket, and a few others' pride will be on the line. Question is, would they do the right thing and offer an apology.
BL.