[CentOS] yum update download only?

Googling for this feature, I saw reports from the yum developer that it 
wasn't yet implemented. This was in mailing list posts from a year or more 
ago. Did it ever make it into the yum code?

I want to start downloading the updates for a server going from 5.0 to 5.1 
and then do the actual installation once I'm on site. I don't want to have 
to wait around while there for the download to proceed. I'd rather have all 
the packages ready in the yum cache when I get there.