Export CSS changes from inspector (webkit, firebug, etc)

I have found the answer to this, at least as of Chrome v14.

While in the Elements section, just click on the "filename:linenumber" link next to the CSS rules. The CSS file that shows up will contain all of the modifications.

This place exactly:

In Chrome, you can right-click a CSS file in the Sources tab and click "Local Modifications"

This shows you all of your local changes. Each revision is timestamped and you can rollback to any previous revision.

See the Live Editing and Revision History section of this tutorial.