I have to admit, I'm rather astonished at this discussion. This is the legal discussion forum and you folks don't seem to want to hear or give credence to the input from the actual IP attorneys. Do tell your doctors they're full of it when they offer their diagnosis? Come on people.
Likelihood of confusion and acts of actual confusion by the public are key points in a trademark litigation. I too, am an IP attorney, btw, though I don't spend much time with trademark issues. The fact that you-all, personally, are not confused is not the issue at all. You are not the public at large. You are sophisticated blackberry consumers and know exactly what is and is not part of the blackberry product line, down to the letter designations for each supplier. Of course you-all aren't confused.
The outcome of a case is never certain. Although I would hope and expect that they sought the advice of outside counsel, RIM is a sophisticated client and, at this point, should have a pretty good idea of what it's doing in the IP arena. They aren't going to be talked into a "frivolous" litigation by some shyster. They'll have made an educatated and calculated decision driven by both IP and business considerations, only some of which we outsiders may be able to surmise.
I will offer no professional opinion on the merits. I don't have all the facts (and if I did, I would probably have an obligation to keep my opinion to myself). As noted, however, RIM probably has little choice about whether or not to pursue it. A trademark certainly has use it or lose it aspects.