They confirmed it on another thread here too but I'll not link it because people decided to turn it into a Dexter spoiler thread.
Luckily I noticed what was happening before I read it any further.
Always look forward to more HD channels.
EDIT - Just read your link and that is almost the same email that our fellow forum member got but with additional info about Sky having to, "upgrade their transmission suites to make them HD compatible".
That's a little more concerning as there are actions required on both FX and Sky so it increases the possibility of delays, but hopefully not.