Hi, I had the same question once on a dutch forum and this was the answer I received from an air traffic controller:
ICAO Doc 7030 (EUR) Regional Supplementay Procedures 17.6.1 :
"Unless an IFR aircraft is receiving navigation guidance in the form of radar vectors from ATC, the pilot is resonsible for obstacle clearance. Therefore, the use of RNAV does not relieve pilots of their responsibility to ensure that any ATC clearance or instruction is safe in respect to obstacle clearance. ..."
As further back up, you should repost the question in the ATC section and get some answers from the ATC guys.
Greetings
edit: this is how I have always applied the rule myself: when on airways or on a direct clearance you are responsible for your own terrain clearance, when being radar vectored ATC is responsible. ATC has minimum vectoring altitude charts which will be below MSA published altitudes.
Note though that although being radar vectored you should always maintain situational awareness in regard to terrain and question ATC when unsure about terrain clearance(also a rule).
Last edited by flyburg; 22nd December 2009 at 20:44.