To be honest, the term is largely meaningless. The abbreviation refers to Technological Protection Measures discussed in proposed copyright legislation. I am of the opinion that any copyright reform based on the 1996 WIPO treaties is (literally) an incredibly bad thing.
What I envision a TPM consultant would do is help organizations audit their potential liability from increasingly treacherous technologies. This may include suggestions on migrating data locked by DRM to stable, documented file formats as easily and legally as possible.
Because honest hardware is increasingly difficult to find, I would likely make suggestions for finding hardware that is as documented as possible, given other constraints. If long-term storage is needed, I may even suggest analog mediums such as microfiche.
Edited: June 15, 2011.