Constant updates is what they want
One of the problems with the Xbox platform or Xbox Live Arcade in general is the approval process that is required to deploy changes. Despite the best efforts of Microsoft, it is still a process that takes time; and with a title such as Mindcraft the updates are necessary and frequent, and sometimes vital to the game. They would like to find a better way to keep the experience the same on both the PC and Xbox 360 platforms.
Apparently, this problem has not gone unnoticed at Microsoft, as the company is working on a way to make sure that the Xbox version is able to receive constant updates. That does not mean that these updates would not be going through testing, but the company is looking at a number of ways to streamline the process and make it so that constant updating for Mindcraft on the Xbox 360 is possible.
While there is no word yet on how they will make this work, the release of new updates every two months does seem to be the goal. From what we have been able to learn, the Xbox 360 version of Mindcraft will be based upon the 1.6.6 version of the game which released just last year before E3. The plan is to get the Xbox 360 version to be in sync with the retail 1.0 version on the PC as soon as possible.