It makes little difference that Ubuntu 8.04 (and other Linux 2.6.24 kernel distros) have been officially released or not as neither are officially supported by VMware Fusion.
Linux isn't supported? News to me. Makes their whole platform a little pointless then.
Given this is a problem with Linux kernel headers, which will eventually make its way into ALL Linux distributions, it's rather serious. Ubuntu is simply the latest distro to be released and bring this to the forefront.
VMware is aware of the 2.6.24 kernel issue in regards to VMware Tools and until they support it by providing whatever it will take to make it work it is a wait and see issue.
From what I can tell in other forums, this is not terribly hard to fix. While I could not personally apply the patch due to some other issues on my system, the patch files I saw changed a handful of lines - almost all involved adding in a different header when running kernel version 2.6.24 or higher.
The delay on this makes me very, very upset.
Before you ask when... I do not work for VMware however the standard line is "VMware policy is to not comment on unannounced features, products, timelines, etc." so until they decide to announce it, it's wait and see.
Something else that makes me very upset - their communication has been worthless.