Multiple domain option for WPMU

Update: The new WPMU DEV Multi Domain plugin is now available which addresses these issues - go grab it now!

Hello.

I want to run one wpmu on domain1.com, domain2.com and domain3.com.

I want all domains to point to the same starting page (not a problem).

Here is the thing:

When users sign up, I want them to be able to select blogname.domain1.com, blogname.domain2.com OR blogname.domain3.com.

Wh't I DON'T want is "blogname" to be taken on all 3 servers by the same user.

Will Multi-Site Manager do this for me? When reading about it, it seems that it will only let me point blogname.domain1.com to domain2.com which is not what i want to do. Please correct me if I'm wrong though.

Thank you.