Any idea how many generations it takes to see degradation in quality?

For instance, If your camera records in MS DV AVI, and you use the video in an After Effects project which is exported as an MS DV AVI, and then import that into a Premiere Pro project, etc...

I haven't been able to find an answer to this. Anyone done any experimenting?

One is all it takes. Will you see it? Depends on the subject material. Shoot a calm ocean on a sunny day and you'll start with rubbish that will just get noticeably worse with each generation. Shoot a clean white wall and it might take several generations before you see anything bad, but degradation will set in with the first dub.

One caveat. If you're editing cuts only and you have an NLE like Premier that does not rerender unmodified DV, there will be no loss. Think of it as a clone of the original with new in and out points.

As with many things in our realm, getting quantifiable answers to questions involving lots of variables is like resolving the square root of pi. You might eventually get the accurate answer but it will be of little practical use to anyone.