iTunes Store: Do Analysts Really Know What Are They Talking About?

Last week, Forrester Research was reporting results of a analysis of online music download business over a 27-month period. They concluded that prediction for 2006 are far from encouraging, if all online music shops are affected by revenue reduction. They reported that iTS sales would have drop by 58% for S& 2006.
Couple of days later, analysts from Piper Jaffray released their own study about iTS, ending up with dramatically different results:

"From Jan. to Sept. in 2005 Apple sold 10.4m songs/week and in 2006 that number was up 78 percent to 18.5m songs/week,"

Not sure they are looking at the same numbers or get access to the same data. It also shows that many analysts are suddenly becoming specialist for analyzing Apple's business when it is time for some juicy operations on the NYSE.
Current rumors or expectations reported by analysts around the supposed to be released iPhone is another example of this buzz built on hypothesis. The iPhone will be released in 2007, the date remains to be defined, I guess only Steve really knows it.