Yes and no. Yes, it's out from Mozilla, and you can build it in Linux from source.
No, OpenSuSE's Mozilla build service doesn't have it out at this time.
They also don't have Thunderbird 3.0 available.
I guess I should have qualified that. It's not out for Fedora yet either that I know of, but I prefer to use the binaries from mozilla. I've had better luck that way.