For users from a blackberry like me and had tetherberry they have finally released a beta version supposedly with speeds up to 6.8 Mbps. I am installing now and we shall see! Just wanted to bring this to everyone else's attention.
Tether BlackBerry | BlackBerry Modem | Tether
I previously used Tether on my BB Storm and it was a fantastic application. It delivered great download and upload speeds with both USB and Bluetooth. In fact, I found it to be generally faster then my Verizon USB Broadband service.
I downloaded the Android Beta version and it worked, but was rather slow and buggy. That said, it a beta and maybe their servers are overloaded with this release. Tether was very good to work with on the BB platform and I suspect they will get eventually come out with an excellent tether application for the Android. Even though I have Wifi tether on my Droid, if they make this work on the Droid as good as they did on the BB, I will spend the money to buy.