Here's the lastest language file for Scottish Gaelic (Gàidhlig) for anyone who wants it, good for all versions up to 18.104.22.168. For extra support, you can also visit www.iGaidhlig.net
To install, save onto your system, the go to Skype » Tools » Change language » Load Skype language file. Same path to go back to English.
Feel free to notify me of any Gaelic-related issues. I can't do anything about the bad plurals, Skype doesn't allow proper plural formatting.
I haven't been able to deal with the conversion to Mac OSX or Linux yet, sorry. Not sure yet either if Skype are goint to bundle it with the main file at any point.