Extracting a tempo from imported audio

Greetings from a chilly Chicago.  Seriously man, it's a real weeny shrinker here today ...

I was wondering if anyone knows of a way to extract a tempo from imported live audio.  Recently I purchased a Boomerang III looper pedal and I love to record my improvisations and then bring them in to Sonar for final polishing.  It would really be a sweet thing if I could somehow determine at what tempo these audio clips are so I could line my audio up with the measure ticks in Sonar's track window for editing ... that way I could extend parts and generally rearrange the tune after the fact.

I know about the audio snapping feature, but that seems to be more for short clips as opposed to entire tunes, right?  At least I couldn't get it to do what I'm looking for ... try as I have.  Has anybody hit on a sure fire method of doing this?

BTW, I highly recommend the Boomerang.  This thing is, in my opinion, the most musical of the loopers currently available. http://www.boomerangmusic.com/Rang%20III.html

Thanks everyone
- scott

Try This
It certainly works on commercial stuff