If Jailbreakme.com doesn't reboot, try this:
I've been trying to go to jailbreakme.com for a million times and it just doesn't reboot. There's no problem with my Wi-Fi... I thought maybe it installed half way and so half the stuff was installed and that it won't want to re-install...
The solution that worked for me was: plug your iphone to your computer. (my itunes was open, but I don't think this matters) Make sure your computer is already connected to a internet source.
Itunes connected to the online store and was telling me to activate. ignore it. Start the jailbreak again (slide for emergency, dial 0 ...blablabla... click on install appsnapp).
This time the it worked like a charm! it took about 30-ish seconds to reboot and slide to unlock comes up :)
I think the whole point was "connect the iphone to the computer and it worked" :D