As of 9/12 there are no Decklink drivers for Vegas 8 available.
Decklink drivers for Vegas 8 will be available "soon", from the Blackmagic site.
SCS is collaborating with BMD dev on this initiative and we'll post some further info here once their new drivers are ready.
Unlike in the past version of Vegas, Vegas 8 will always use the current Decklink drivers on the BMD site, and we expect this to be a positive step for everyone, especially if you use multiple products that connect to Decklink hardware.
I'm more than happy to hear this, I'm thrilled! Using the Intensity to view real-time preview to an HDMI-equipped HD monitor will be great. When that happens, I can delete that evil Adobe Premiere CS3 off my hard drive for good. :)
If you mean hardware support, I think it is a beyond safe assumption that this is not coming anytime soon (probably not ever, other than GPU support which they can only hold off for so long).
I hear tale that v6.5.1 works... but I'm no longer on a box w/ a BMD card.
However I DID install the v6.5.1 drivers/software on my box so I could have the BMD CODEC's & Decklink Capture Utility. I'm sure there are other benefits of it too but these are the one's I use most.