Is it possible to have subdomain.example.org hosted at dreamhost while example.org is hosted on another hosting service?
Yes! Asked and answered in the forum already. "Search" is your friend!
[hangs head in shame, bows with gratitude, silently withdraws]
Now I feel terrible! I was just teasing you...it's really hard to locate this stuff sometimes. Welcome to Dreamhost!
Oh, the abuse is free, BTW.