While this sounds like an ideal chain of events following the theft of your Mac, Damien brought up a couple great points as to why this software might have a limited, if at all, rate of success. First, the typical computer thief might find a way to erase the stolen computer (which makes me wonder what kind of people Damien hangs out with). Second, if you're a portable notebook user concerned about security and theft, you probably don't walk away from the book while logged in, and (hopefully) you don't set your book to automatically log in anyway. As far as I understand how this software works, both of these practices would render Undercover useless, as I'm pretty sure you need to be logged in for the software to work its magic.
Ultimately, you should probably check out more of Undercover's abilities and inner workings before jumping on it. Orbicule, the makers of Undercover, offer a customer service/sales online chat option if you'd like to talk to them more about it. At the end of the day, it's at least nice to see some new thinking (even if it might not be fool-proof) in terms of portable computer security.