Yeah they can easily be updated, and that's a fantastic idea!
Someone would have to make them though, and make rather nice looking ones. Also, try to keep them approximately the same size as the current icons. Too-big icons goof up text and tables.
1. get a list of the file names and the emoticons they stand for redesign them as aqua styled drops and save them out with the same filename, keeping them same pixel dimensions and being mindful of filesize.
2. after the files are created like that, stuff them and mail em to Admin...
3. Admin unstuffs them and drops them in the "/forums/images/smilies/" directory.
I really think this site needs some serious sprucing up.