I have found that there is no version number anywhere in any of the arduino library, firmware, and hardware, that I have come across, except for the occasional R2 R3 on hardware revisions. I do version numbers (all contract work, libraries, firmware, and PCB designs I do). This makes it easy to track down where the problems are. But Arduino team, you have a very different "use the latest thing" philosophy! Take the WiFi shield for example, there are multiple firmware and library and they don't all work together. I once downloaded some version of the firmware and library but after a few weeks, those versions are gone and replaced with the latest thing. How am I supposed to know which version is which, especially after I found out the latest thing you published isn't exactly working? Just read a few posts here to see how poorly the wifi shield firmware is:
I can't even make an effective complaint. I have no number. I can say that an earlier version of library works with wifi R3 (no numbers) but the later version won't. That's it! So come on! You don't have just one arduino and one thing going on anymore. The sooner you slap on some version numbers, the better off you are. You're in a deep hole already so help us and help yourselves too! Add version numbers.