You know, sometimes you get stuff in your tip jar and it's just too far fetched. However, I can't ignore the possibility of this rumor being true. So for now I'll stick it under the rumors column and you can take whatever you want from it.
Basically, some unnamed person has tipped that Microsoft will be dropping the price of the Premium 360 another $49 on the same day that GTAIV gets released. This mwould be a smart move for Microsoft as we know millions upon millions of people love the GTA series.