A couple of days ago, I emailed Henri Heinonen, a developer working on adding Bitcoin support to the BOINC project. I wanted to let him know about Primecoin. Here is the reply that I got:
Thanks for the info! I'll look into this. My project is here: http://www.bitcoinutopia.com
I have been thinking about adding mining support for Namecoin and Litecoin and possibly for other altcoins, too.