Shelley, looking good.
My only question, so far, would be how scalable will they be in regards to size? My personal preference lay with using smilies that are close in size to the 'stock' versions so that when they are used inline in the middle of a paragraph, the formatting is not distorted.
OOhh... thinking out loud... how about an exclamation point, thumbs up, & thumbs down so that they can be used to replace the post icons as well?