Dealers and BMW will not just update mostly due to the risks associated with programming. Failed control units add up in price quickly. Sometimes if you're lucky, you can get updated for another reason. Re: nav, telephone or audio system software updates needed. The entire car gets updated at the same time, so in that case you're good to go!
Edit: ISTA/P 2.46 is referred to as 231E around here. 2.47 is referred to as 240E. I'm not sure what 2.48 is referred to as, since it is only a couple of weeks old. I've yet to see any data on available tunes or tuner experience with the latest version, if there is indeed a relevant update to the previous version. Perhaps some one with experience in the tuning aspect of this platform will stumble in here and offer their input.