Since it's been the subject of a great deal of discussion and speculation, I'll throw in my opinion: I think it's dumb of BMW to revise LL-01. If it's a newer, more demanding (or just different) specification give it a new and unique designation. Case in point: my 1999 E39 originally specified the latest spec when it was manufactured - LL-98. Then around 2001 came a new specification and they called it LL-01. Now, they've revised LL-01 meaning that oils that would have been perfectly fine for an engine manufactured before the revision are no longer "approved". Like many others, I just look for the A40 spec or MB spec and call it a day (M1 euro or Edge euro for multiple reasons).
To my way of thinking BMW specs seem to be based on test spec v.s. date of issue (hence LL-98, LL-01, LL-04) so in a sense they are going retroactively changing a spec from a particular time (thus vehicles produced in that era). The ones you mentioned like A40 or SN or any of the others are just alphanumeric designations with no implication of era. I believe it's implied that say SN motor oil is fine for a car originally spec'ed for SL (correct me if I'm wrong, I'm assuming that to be the case). Whereas in this case LL-01 today doesn't meet the requirements of LL-01 for older cars. Logically confusing.