They're not advertising that. The closest thing they say on their web page is "no data caps," which doesn't imply that you can use the connection to run any service you please. Besides, I'm willing to bet that they have more detailed terms of service that must be agreed upon before receiving service.
We know they don't mean that, and they know we know they don't mean that, but I don't think we should let companies get away with lies like that just because everybody's used to the lying.
edit: Wow, down-voted for out pedanting the pedants. That's some cognitive dissonance there.
What, if anything, does this mean to you?
Many ISPs offer "up to XX Mb/s" with no caps. In the event of unsustainably high use by some customer, that customer might have their maximum speed lowered to ensure the network quality of other customers.
It's impossible to provide unlimited data anyway, because the maximum amount of data per month is bounded by (length of month * permitted data rate)
Which is why they should be legally forbidden from advertising that they are slling 1 Gbit of unlimited-use bandwidth.
How hard is that? Don't advertise what you're not selling. When you say "unlimited use 1GB synchronous connection" and that's not what you're selling? That's illegal. It's called false advertising. Sure no one gets nailed for it any more, but that doesn't make it right. Advertise that you are actually selling a "restricted 1GBit synchronous connection with limits on what ports you may listen on, limits on upstream use, limits on what applications you may use on the network", etc.