If you don't mind using a big fat plugin (over 50KB in minimized version), you can try my TWtid which offers multi-line rendering mode in table cells, see
http://twtable.tiddlyspace.com/#[[TWtid--Example--Lists in Cells]] for example. If you don't see lists rendered properly, check the multi-line mode option and reload the page, it should work. With TWtid you use <br> in the cell text for a new line, the plugin translates it into the new line character and wikify the content in the cell to produce a multi-lined result.