No invite but in the meantime you might get a kick out of this.
Seems pretty similar in features BUT I only know a little about skitch. I know more about Jin because I researched for my blog articles.
Jing - Free HI RES ScreenCasting from the Camtasia People
Heres the Jing video showing what it does.
How do I use this thing called Jing? (Jing Blog)