Seems the rumor mill is churning again. It seems that BMW may be placing a new ECU in vehicles rolling of the production line in March and going forward that may detect engine modifications. Rumor has it that it is a new ECU aka DME (hardware not software) that could store any abnormal readings and then these readings or CEL's (Check Engine Lights) could be read by your dealer next time you come in for warranty work or an oil change.
If this is true then it does seem to make sense as BMW is slowing entering it's own in the release of it's "BMW Performance" Catalog for those of us seeking a few extra HP. And "BMW Performance" could be another source of revenue for BMW as well.
Again all rumor and we don't know how this will affect any "tunes" or modifications going forward but we will keep an eye out and an ear to the ground let you know.