Coolreader in OI currently has basic dictionary support. The dictionaries are in dict format (
http://www.dict.org/bin/Dict), in which there are many nice and free dictionaries available. Very soon I'm going to make a dictionary application, which will likely serve as the main dictionary app for the openinkpot platform. Dottedmag wanted to rewrite in C the libtinydict library that Buggins (the author of coolreader) created, which should be a quick job. I'm just waiting for that to be done in order to make the dictionary app. So yes, we're going to have full dictionary support, and fairly soon.
Cheers!