I took the week off
It's amazing what doesn't happen when you take the week off. You can still meet goals if you take periodic breaks, but don't expect projects to work themselves if you're not working them.
Here's what I mean: I took the week off from my Twitter Immersion, while I nursed my kids and myself back to health after a terrible bout with the stomach flu. My tweeting was rare, and when it happened they were automatic tweets from Foursquare.
During my first week of Twitter Immersion, I averaged 4 new followers a day. The week void of substantive tweets brought in one follower - one in the entire week. My elementary conclusion is that people want to listen to you if you have something of value to say.
I'll return to my schedule of regular Tweeting and intense focus on all things Twitter tomorrow. Prediction: I'll pick up around 20 new followers next week.