NEAT and Micro-Workouts

I was interested to read this bit from Skwigg on NEAT (non-exercise activity thermogenesis). It's basically the calories you burn from fidgeting. Squirrelly people burn more than we relaxed folks.

This got me thinking about a crackpot idea I've been mulling over: the concept of micro-workouts. I recently read that you don't have to get your exercise all in one big chunk, you can break it up over the course of the day. So six 10-minute sessions is as good as an hour straight (I'm not advocating long cardio work, but some folks dig it). What I wonder is, how small can the workouts get and still be effective? If I take a two-minute break every fifteen minutes during the workday and crank out a semi-quick 500m on the rower (I work at home), is that as good as rowing for an hour (32 2-minute sessions)?

I doubt it does anything for my strength, or even much for my conditioning, but what about my metabolism? Tying this back to the NEAT ideas, I imagine that kind of work would count as some serious fidgeting. Just some half-baked thoughts late on Monday evening...