Well I thought I was going nuts! Until I found this thread, my 2.2 SR 15" makes this blipping noise quite frequently as it happens, can anyone shed any light on this issue. My wife's 2.4 Penryn does not seem to have this issue, thought he fans on hers do make a lot more noise then on my SR.
To be honest, this sound only really bothers me when I'm in a very quite environment, which is not that often, so until Apple come up with a solution or order a recall I don't think I'll be doing the software patch suggest on page 9.
Will keep in touch with this thread however, this certainly appears to be a widespread problem.