There's been a lot of talk about BlogRush recently and bloggers seem to be divided into one camp that subscribes to the "useful blog syndication tool" idea vs. another camp that paints BlogRush as an "evil pyramid scheme".
On the surface - if you look at their video - it does indeed appear to be both. There is clearly a benefit to the individual blogger who adds the widget to their site, and there is also clearly a pyramid scheme involved. But in contrast to evil pyramid schemes based on money (Amway, etc.), which can rip apart families and friends because you suddenly trying to sell stuff to them all the time, BlogRush is solely based on trading impressions of syndicated links. I see nothing wrong with that.
So I would term it a "useful blog syndication tool based on a non-evil pyramid scheme".
I do, of course, expect them to eventually open their syndication network to advertisers who can promote their new blog for pay across this network. But there isn't anything wrong with that either...
Conclusion: I'm going to give it a try (see sidebar on the right when you visit my site) or go to the BlogRush website to learn more and/or sign up your blog.