I just found at joe's site link to Washington Post's article which is informing about decission which was made at Microsoft to open access to system "guts" for security software providers. If it is true, and I don't have any reasons not to belive WP it will mean that security software providers like Symantec and McAfee will gain access to Vista's kernel level.
Will this make more good or bad? – I don't know for sure but I would feel better with access to system kernel locked for any third-party software. If I say "any" I mean AV products and viruses itself.
The fact that Vista was protecting its kernel in a new way from accessing by external program was suposed to be one of a key new features which will influence system security in performance. How it will change and how it will affect system performance and security … will see in a near future.
Update: another press infomration about this can be found in International Herald Tribue. We can read there that this step was made to comply with EU regulation and to prevent possible delay of Vista on European markets as a result of European Commission actions against Vista.
In article posted at TechWeb we can read that this doesn't mean that Microsoft will give up Patchgurad as security feature of Vista operating system. From this article we can read that this decission means that Microsoft will help security vendros to interoperate with system in a more legitimate way.