Today I was poking around on the internet to find out the copyright restrictions for the emoji icons that are used on the iPhone. A quick search lead me off to site that explains a bit of the background of the icons themselves. I guess they were developed by Japanese mobile phone companies as a way to send icons in the message without having to send the actual image data. Instead a simple code is sent to the phone that tells it to display an image that was stored on the phone. Here's the blog post that explains the history and gives the full run down of the emoji and the licensing/copyright details of the Apple version.
This link shows the variation between some of the different icons from different makers.
Also during my searching I came across the Unicode site and they have various collections of icons. The above image is something I patched together from a few different links. They are available online in PDF format. Here is the first, the second and the third.