How important are teaching portfolios in obtaining an academic position? I have been recently introduced to the idea of teaching portfolios, that is a collection of teaching experiences and references made by peer educators. Their supposed purpose is to go along a researcher CV when applying for a position in academia, i.e. assistant/associate professor.

Any first hand experience?
This may be useful for someone considering a career at a teaching-first school, but I've never seen such portfolios asked for or even considered at research universities in the US and the larger European countries.