If I remember right the 3.6 is available in the US in the Passat. The Passat B5 and the Mk5 Golf share the same platform, so It's not unlikely, I guess it just depends on if they think it wil sell in sufficent numbers.
I've had the privelidge to drive a 3.6 passat... all I can say is that if that engine goes into the Golf, it
will be the end all, be all of every golf evAr made. 280hp in the passat was insanely torquey and and had awesome speed to it. The new 3.6 is a lighter engine as the block is aluminum and felt just awesome to drive despite the size and bulk of the Passat. I have to expect it will be made, in the US the R32 came at the very end of the production of Mk4's; I'm going to assume Vw will release the R36 sometime around the time the MkV ceases to exist also. It is actually rumored to be arriving in the States around 2008.
Is the 3.6 available in the Uk yet?