We've had to regress several times on the patch which slowed down the entire procedure. The reason work on this progresses slowly is that we have very limited space (4Mb) to put the patch content in, which forces us to use all kinds of tricks to fix certain things. Sometimes these tricks backfire and we need to try another approach, but given the size of the game and the time it takes to QA it, it happens that we only figure out that one of the tricks backfires after several days of testing.
In any case, we just got the pre-certification reports and they tell us that if we fix one last thing to do with a slider in the options screen, it should be good to go to Microsoft. Submission of the patch is scheduled for this friday, and then it should take a couple of weeks in Microsoft certification before they can put it online.