@Jelmer, thank you for the reply .
I hesitate between two frameworks for my new project (Fuel and Jelix). If I choose Fuel I will definitely wait 1.1.
P.S. English is not my native lang, so I might sound bizarre sometime...
If I were you I'd wait for 1.1 stable. I'm using Fuel since the first (beta) release and I really love it (but I can only compare it with CodeIgniter). If you can't wait I think it's safe to use the upcoming 1.1 beta.
We're happily using 1.1 in it's current state in our development environments and haven't had many issues. If you clone each of the fuel repos (fuel/core, fuel/orm, fuel/oil, fuel/auth) into the right place in your project you'll be able to easily update as commits are pushed out. That's what we're doing.