What I think is interesting about the free-to-play period (due to website collapse) is that it may actually be a massive boost, because it gets the game client onto a lot of machines. That doesn't sound like much, but here's where it gets interesting: the client auto-updates itself, bringing in new content and features as they are built. To continue to get updates (AFAIK) you must log in with your paid credentials. You can continue to play the 'free weekend' version without doing so, but you won't get any updates. Thus people can continue to play and be addicted, and that 'Register' link is there waiting on the main menu when the urge for the
new hotness overcomes them.
Also, kudos to Notch for supporting Mac and Linux. I guess we're getting to a point where, for indie games at least, a very compelling experience can be built using a less-than-optimal platform (in this case being Java, which heretofore hasn't been used for games a whole lot).
By the way, it has even had TV coverage here in Australia: http://www.abc.net.au/tv/goodgame/video/default.htm?pres=201...