With the dawning of beta, the price will be raised from €9.95 (around $13.20) to €14.95 ($19.85). Furthermore, while the alpha version of Minecraft promised purchasers all future updates for free, the beta version will not.
"Please note that this change only affects people who buy the game after December 20, so if you got the game for during alpha, you will still get all future updates for free, despite this change," Notch stresses. "A promise is a promise."
As to what entering beta means for players, here's what Notch has to say:
With Beta comes a larger focus on polish and content, and we'll start early on with adding proper modding support with a stable API, and we'd love all input we can get on this from the modders out there. We'll also add some kind of non-intrusive narrative to the game to help drive the game experience early on, and to provide some kind of late game goal. There will be a bigger focus on testing and stability as well, with more time between updates."
If that sounds tempting and you want in on this whole 'Minecraft' thing everyone's talking about, you should buy before December 20 to be promised free updates.