Resolution Of Channels On Sky Digital

I remember reading that ITV 1 broadcasts at a lower resolution on Sky Digital than most other mainstream channels. Does anyone know what this resolution is? Also, in perfect reception conditions, does the compression scheme used by ITV on freeview produce higher quality pictures than ITV's compression scheme on Sky?
Finally, somewhat related to this, when is Sky going to launch the high definition service announced last year?

AFAIK, Sky were never going to launch an HDTV service (or at least had now current plans for one). What did launch was a european HDTV channel. Is that what you meant?

http://www.digitalspy.co.uk/article/ds14675.html

It seems that it will launch in 2006.

ITV apparently use around 544x576 for their digital satellite (aka Sky) services, though they use 720/704x576 for their digital terrestrial (aka Freeview) stuff.

The Beeb use 720/704x576 on both platforms.

(This means when ITV show pillarboxed football on Sky the 4:3 centre area is only being carried in approx 400x576 - hence the complaints about a "soft" picture on ITV via Sky during Euro 2004)

ISTR that ITV News Channel, QVC, BidUp etc. are all 544x576 on Freeview as well.