Update: Mega crossed the 250,000 user mark and massive usage has brought the site to a crawl. So far, Mega has won the day.

He built it. They came. Then the government took it away, and so he built it again. And they came yet again.

Today, an hour after he flipped the switch from no to go on Mega.co.nz, precisely one year after Megaupload was scuttled by the government, Kim Dotcom announced that his new service has totted up 100,000 registered users in its first hour as a live product.

He openly wondered if the feat made Mega the “[f]astest growing startup in Internet history?” TNW isn’t sure about that, but hitting six figure usership in double digit minutes is damn impressive regardless.

On the eve of the launch, chatter was loud that Mega would be launched under a .co domain, and not a .co.nz TLD, over fear of the New Zealand government taking punitive action. Thus far that fear appears to have been either mistimed, or groundless given that Mega is up and cruising along.

Given the stunning demise of Megaupload, which led to the freezing of endless quantities of both pirate and legitimate data, the launch of Mega is construable as a challenge of sorts: take it down again, Kim dares you. Kim himself has called the new service “100% Safe & Unstoppable.” Another challenge.

And there is one more one more, from Kim to the MPAA. He released the following image, saying “Look at this @MPAA. Lets talk!:”

2013 01 19 10h58 50 Mega hits 100,000 registered users in one hour as Kim Dotcom teases MPAA with MegaMovie screenshot

We’ll see what happens, but the site is proving to be tremendously popular. A prior tweet from its founder noted that it had gone from “0 to 10 Gigabit bandwidth utilization within 10 minutes.” It’s likely using more now. When the dust settles, Mega will likely have a seven-figure usership by the time it celebrates the conclusion of its first day.

Top Image Credit: Niklas Freidwall