An example how I use different alphabets under Ubuntu:

(default, the Estonian, mapping) - x q w y ä ö
[Shift]+[CapsLock]
(the same keys, Russian) - ч й ц н э ж
[Shift]+[CapsLock]
(the same keys, Esperanto) - ĉ ŝ ĵ ĝ ĥ ŭ

One keyboard, two layouts, three mappings (did I use the "layout" and "mapping" aright in this context?).
Harri.