Soon very soon.
Only info I see is "Early 2008" which could be from now until June.
It was shown, at one time, that it was going to be on DirecTv by the end of 2007 but that did not happen.
Toon Disney HD will be coming soon as well.
Found this.
DIRECTV Disney Channel HD
In early 2008, DIRECTV will launch Disney Channel HD, a simulcast of Disney Channel featuring the channel's blockbuster Disney Channel Original Movies in high-definition as well as original live action and animated series for older kids and Playhouse Disney programming for preschoolers.