I don't think many people will upgrade right away because they'll lose all their addons. I know I'm going to wait at least a few months after the final version just to make sure. And didn't vB 2 come out with a hack to add a Quick Reply function to threads? Same sort of thinking I guess....
I can always wait until it's released and pick through the code to add it myself though... Just thought it would be better if someone experienced could do it
I think it appears straight away because it has something to do with inline coding on 3.5 or something. I'm no expert, but I don't think anything like that can be coded for 3.0.x or pre 3.5.