I posted the original LTT code in July 1999. We are December 2011.
The continued lack of a holistic tracing infrastructure for end users in Linux while other OSes have been shipping with this stuff for decades likely demonstrates that existing political equilibriums and fear of confronting the egos of certain kernel developers are being placed above user needs. The same stuff early Linux proponents were pointing out as a deficiency of the development of the older unixen.
Disclaimer: no relationship, other than possibly the name, exists between current LTTng work and the defunct LTT project. I do NOT speak in the name of LTTng in any way. Nor have I in fact been involved with in any way other than the occasional "so where's tracing these days?" sent to Mathieu. I left tracing altogether in 2005 in utter disgust after fighting for 6 years to get it mainlined. And I have no regrets of having done that thank you very much :)