Upon trying to order a Xen-HVM VPS from turnkeyinternet.net (They advertise both 32bit and 64bit version of FreeBSD 8.2 for use on their VPSes as installed from ISO images). Unfortunately after several attempts their engineers could not get FreeBSD to install onto their systems stating that FreeBSD is not currently compatible with the "Current Stable version of Xen". 

The heading of the last email they sent me was as follows: 
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HI Karl, I spoke with the service manager and Sales Manager in regard to this - bottom line the FreeBSD and derrivatives is not compatible at this time after a recent update on our Xen/SolusVM system. While it was at one time working, its compatability today appears broken (Researching it with engineering after they tried last night to assist you, turns up a known issue with BSD and their multiple different spin offs with certain Xen platforms).

All that said, I don't want to waste your time either - as I appreciate your frank comments, and in short we dropped the ball here in terms of having the support for BSD OS's like we showed. I do have engineering working on it for the future, but its not going to be an overnight item by any means (it requires a customized Xen kernel, outside the stable path of our SolusVM system) and its not something we will roll into within days, or even weeks for future support.
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They did not specify what was the current 'stable' version but I'm guessing the 4.x branch as places like RootBSD are still using 3.x possibly for this reason. They were not able to get NetBSD to install either.

Fix: 

At this time I do know of any fixes.
How-To-Repeat: Mount a FreeBSD 8.2 ISO (32 or 64bit) into Xen-HVM and attempt to boot from it, You'll get a repeating crash screen showing that BTX has halted over and over again.