I have now confirmed The Clone Wars is natively 2.35:1. Episodes are shown at their OAR on Sky HD, but are cropped to 16:9 on Cartoon Network.
I've made screen caps to prove it:
All caps made in MediaPlayer Classic Home Cinema, as PNG files at full size. Full Size for the Sky HD encode I have is 1280 x 544 (2.35:1), although the shows are broadcast at 1080p. Full size for my Cartoon Network version is 1280 x 720 (16:9, or 1.78:1); don't know what the broadcast resolution is. Sky HD caps are from Episode 11. Cartoon Network caps are from the recap of Episode 11, at the beginning of Episode 12. Images shown here are JPG, at a constant height of 320 px.
You'll also note that SkyHD doesn't have any annoying logos on the picture at any time.