mu-plugins

These are two semi-related questions. First, in 3.0, will the mu-plugins be changed to some other folder name, or is it going to stay as mu-plugins?

Also, I'm starting to code my first plugins, which I'd like to run in MU and regular WordPress, or scale smartly when there's a multi-site install. Should I be coding, expecting my plugins to live in mu-plugins, or in plugins? Or some mixture.

Honestly, I'm still confused about the two different folders and when one is used vs. another.