But I believe they're already in the game cache.
(seeing as the skill cape inventory icon shows up at the 'Skill Mastery' in any of the skilling guide interfaces)

Are there skillcapes ingame (seeing as skillcapes were released on the 18th of October 2006)?

Sure! c:

Selling 500 Magic Logs for 800 gp ea!  ;D

Nvm  ::)

Best of luck with it!  ;D