Unlike the X Input Method framework which is tied to the X windowing architecture, IIIMF is a modern, platform and windowing system-independent input method framework developed by Hideki Hiura, the original author of XIM.
IIIMF is based on a modern client-server architecture which allows multiple language engines to run concurrently. IIIMF not only provides an X Window client framework (IIMXCF), it also provides client frameworks for Java2, Emacs, GTK+, QT and Windows in addition to the generic libiiimcf C client framework library.
You can currently try out IIIMF in Redhat's Fedora Core 3. Other Linux distributors are certain to follow suit in the near future.