What's the standard font called that comes on droid x running 2.3?
Prior to Android 4.0 (aka Ice Cream Sandwich) It's called "Droid", and comes in Serif (Regular, Bold, Italic, Bold Italic), Sans (Regular, Bold), and Sans Mono variants.

A new font family "Roboto" was released with 4.0.

Wikipedia article on Droid (font)

Google+ post on Roboto