Also, Anandtech has a system in hand and has done the first half of their review, they specifically mention the heat is not too hot.
Here's what they have to say:
We are currently benchmarking the M:855 in more depth, and part 2 will cover what has become known as the AnandTech standard mobile review, as well as diving into the battery life of this powerhouse notebook. Voodoo claims that it fairs better than their Centrino notebook, which is indeed a very exciting claim to make. Considering it based on a K8T800 chipset and uses an Athlon 64 DTR, we aren’t expecting incredibly high battery life. After all, these are desktop and desktop like components, which aren’t designed to be that forgiving on power consumption. We will know more on this subject soon once we get the final benchmark numbers in.
In the meantime, we should mention that our system comes with a price tag just shy of 3,600 USD. (3,578 USD with 1GB of system memory to be exact, but we only used 512MB for benchmarking purposes.) With this price tag and considering its hardware, Voodoo is no doubt continuing to go after the gaming market. So far so good, as the M:855 comes with a great feel to it: tactile keyboard, crisp screen, etc..., which we will explore deeper in our part 2 coverage. The system gets only so warm as some of the Intel based desktop replacements we have seem (Pentium-M, Pentium 4 533MHz/800MHz, etc...), and is surprisingly quiet compared to many desktop replacements (about the same as the Dell Inspiron 8600 when idle in this regard). At the moment, we have no qualms about recommending the Envy M:855 for gamers or enthusiasts, as it performs extremely close to a desktop AMD Athlon 64 3200+ system in some scenarios