Code highlighting is "must have" feature for any tool that deal with the source code, however it's not a core feature for Snippets as it is for code editors. We did not wanted to spend a lot of time creating our own editor, and we did not know any good implementation until recently we discovered Ace Editor.
Ace is an embeddable code editor written in JavaScript which makes it an ideal solution for Snippets that we can use in desktop apps for Mac and Windows and in a web browser for our Web app as well as some other secret tools that are coming out soon. It is the same editor that is used and maintained by Cloud9 IDE, so it's very solid, fast and well tested code editor. During the development it shows great performance and we like it.
Please download/update Snippets and enjoy.