Five has not made any announcements about HD services launching any time soon.
ITV HD, which will be accessible via the red button from ITV1, will launch "soon" and will feature two/three hours a night of HD, only on Freesat.
C4 HD is currently exclusive to Sky. Virgin Media have the rights to the channel but do not currently do so and have not confirmed when they will. Here's the link on that.
There's a misconception that there's a huge amount of UK HD content being filmed and it's just a matter of setting up the channels: that ain't the case. HD filming is still very much a rarity.
Frankly, if you want HD Sky is the only option that will give you sufficient programming to satisfy you. HD costs and is a sizeable investment for a broadcaster, and neither Freesat nor Freeview will carry significant amounts of HD for some years.
Anyone checked out the presentation Berkett made to investors? It confirms the shutdown of the analogue network and release of more bandwidth for faster broadband services...and possibly more TV too? I've posted my views on the VMHD blog, but you can read the full presentation here.