Craig Latta's evolving project at http://netjam.org/spoon which starts from a tiny (~100kb) image and small VM (using his Flow plugin for I/O), as well as a full regular Squeak image with special support for remote message-sending as well as remote browsing, editing, compiling, inspecting, and debugging (mostly by a proxy SystemEnvironment object).
The tiny image loads code on-demand via secure socket connection (SSL) from the server image.