Chris, the ".something" is a "dataglob". Dreamhost uses this to "group" directories for ease of management.
You can find out more about them, and their use, on the wiki, or in several posts on this forum...just search for dataglob.
The main thing is, they are "transparent" for your purposes (home/yourusername symlinks to them), so you should not use them in your programming, or your script configurations - just use your normal /home/username path. That way, if the "dataglob" changes with a Dreamhost re-configuration, your script will not break.
Some scripts will report the path including the "dataglob", as they read the environment/server variables.
edit: A couple of useful links:
Dreamhost Honcho Dallas on dataglobs
Dreamhost wiki article on dataglobs
or, search the forums/wiki for more...