From chat with Tim:
tsala: re. define roles in 2.0, I thought it had a nice search which started finding stuff as you typed
tsala: but now I can't find the search anywhere ;(
tsala: was I imagining it?
timhunt: No, it did exist.
timhunt: But it will only work if JS is on. And the JS works without errors.
timhunt: That is odd. No search JS, and no JS error.
tsala: I can't find any 2.0 site where it works
timhunt: Oh, yes there is an error, once I open Firebug.
timhunt: File a bug on Sam H saying that the M.core_role.init_cap_table_filter code in admin/roles/module.js is not working.
timhunt: That is probably the sort of bug he eats for breakfast.