First of all, I'd like to say: nice graphics, Jamie! But...
...I have a couple of comments! Before I get told off for being a stiff-necked stick-in-the-mud, allow me to explain: I'm finding it very difficult to work out the emotion each of the new icons represents, compared with the 'classic' smileys. I find the graphics to be a bit too 'busy' - it takes me several seconds to identify the expression on the Muppet's face (I'm still not quite sure what Pepe - it is Pepe, right? - is expressing!). They're just about Ok on a 1024x768 LCD panel, because the display is pin-sharp, but on a 21" CRT at 1600x1200, the icons are pretty much illegible. For example, I'm typing this on my laptop, about 12 inches away from the screen, and I can see - if I look closely - that Ernie is sticking his tongue out. On the CRT next to me however, where I normally sit much further back (to reduce eye-strain), it's just about possible to tell that it's Ernie, and that's it.
I don't know if either of these would be possible with the forum software, but how about a) providing both the 'Muppet' and the 'classic' smileys, so that posters can select which set they'd prefer to use in their posts; or b) allowing the user to select which set of icons they'd prefer to see when viewing/making posts?
Anyway, this isn't intended to be a whine or flamebait, it's just my thoughts! :-D