Many signs and symbols have been added to our writing system thanks to the international standard called Unicode. The latest version of Unicode contains a repertoire of 136,755 characters covering 139 modern and historic scripts, as well as multiple symbol sets. Think for example of the € sign. If the EU might decide in the future to alter this symbol (or expand with multiple currencies, you never know...), this will have to be added to Unicode again and to the most commonly used typefaces (which is why these also have to be updated regarly).
To add a sign or symbol to Unicode, you need to present it to the Unicode workgroup. Last October, Creative Commons submitted an initial proposal to get CC license symbols into Unicode, and recently submitted an updated application after some feedback from the workgroup.
The new proposal presents the CC license icons as graphic symbols. They have come up with an inclusive approach that permits public access to the graphic symbols, without affecting the trademark rights in the specific icons. This is similar to how companies like IBM have managed their marks with Unicode.
Creative Commons also asked the public some questions about how you currently mark works with CC licenses. Of the 709 responses, it seems that more than half (441) use the CC license icons or buttons to indicate the license on a work. Many more (681) said they would also like to be able to use the CC license icons in text (Unicode!) to indicate the CC license. Maybe this wil soon be the case, as soon as the new proposal is accepted.
(Thanks to Jane Park)