HD-DVD is dead. There are almost no instances where it should ever be used. I say almost because I have one client that adopted it very early on and uses it for a specific purpose in-house, so I deliver on it for them. They are literally the only client I use it for and they are the only people I know that use it.
These is a thread below this that we just discussed delivering in HD. You should read it as it has some good comments. There are a lot of assumptions you have to make to deliver HD to someone. While you are typically safe delivering a BD-R, even this isn't a given. Talk to the person you are giving it to and find out what methods they have to play it. Perhaps an HD Quicktime or WMV file on a flash drive or DVD-Rom is the best way for them. If it seems uncomfortable to ask up front, try to spin it into a chance to demonstrate that you understand the technology and the current limitations of it.
Specifically to your question about Compressor - I believe versions 3.5 and 4 can both burn simple Blu-ray Discs. Toast and Adobe Encore can also do this, both with a few more options than Compressor.