Let's not. Please. Personally, I find the colored smileys that so many services insert awful:
- They break the flow of text.
- They tend to be larger than normal characters, making the line they are in taller and so inserting spaces between lines.
- Unnecessary overhead (OK, extremely minor issue).
- Ugly (very personal choice of course but there you go).
If we're going to add something to chat let's make it useful, something like having code blocks displayed with a different background like this so we could easily paste commands in chat. As it stands, we just get a fixed width font, no background and it is easy to get confused.