This post title is perhaps a bit harsh and may not be justified, but 2 things are true: Blogrush is an externally hosted widget that will increase website load times, and Blogrush is growing exponentially.
See this alexa graph for Blogrush:
See what Blog Rush looks like:
I have just started using Blogrush and to get the most value out of this blog widget you will need to be an early adopter.
The main benefits of this service is allowing you to find new sites related to your blog. There are probably hundreds of people in your niche that have interesting things to say, and you will never read them. This is like personalized autodiscovery for blogs, and gives you an indication of what you will find, unlike services from stumbleupon.com. Also, Blogrush has an affiliate program, while stumbleupon does not. What is cooler than getting credits for new signups?
Video demo of Blogrush