I've recently added emoticonsto my .Text blog. If you could see the code, it might look familiar. Heh, that was pretty easy. I did make a change or two to the source of .Text and also added a key to the web.config's appsettings node.
The magic happens in a method called StripFTB (for free textbox, the editor used for this app) All I did was add a call to the new Transform class, added the appropriate text file, and we're in business.
If you haven't checked it out yet, .Text is a real good app - it's been real easy to make changes to it to 'fit my needs'.