I'm going to do a new install of Wordpress. new 3.0 version is coming. current stable version is "WordPress 2.9.2" and "WordPress 3.0 Release Candidate" the last release before final version 3.
So for now i should setup 2.9.2 or 3.0 Release Candidate?
will i have to replace all files to RC upon final release?
What are cons to use Release Candidate version?
It's not stable. There are likely bugs that may spoil or impede your progress with it. There may be security issues. There will likely be problems with certain plugins that are only maintained up to 2.9.*.
If you're comfortable navigating their bug tracker and you're unlikely to take this site live before the final release is made, by all means, suck it and see.
But if this is something you want to launch tomorrow and you need it to work, go with stable. If it's any consolation, the update process is pretty robust.
The fact that they're some months behind their original roadmap might be cause for concern.
As we have reached RC2 and there are usually only two release candidates, you could wait for the final version to come out within the next week (or at max 2).
But also installing the RC2 is OK, I am using WordPress since Version 2.7.1 and there was never a issue updating it to the newest version. Just backup your database in case anything goes wrong. But usually nothing goes really wrong. Just run the automatically update and you should be fine.