HD2s come with 6.5 as standard, WM7 isn't out year, though the rumour is that the HD2 will get an upgrade, like the TP2 did for WM6.1 to 6.5.
Either way, cooked WM7 ROMs will eventually appear, and we can stick it on unofficially.
Pandora is the name of a ROM made by a chef on XDA-devs. It's tweaked out the box, and has performance gains over the stock HTC ROMs you get.
HD2's will probably be running windows 7 2-3 months before a phone with it bundled is out too.

That's what happened with WM6.5 as well.

No, Jailbreaking only allows you to install non apple approved applications. A Custom ROM allows for much more tweaking and customisation.
I doubt MS care, as long as the Device gets bought and people use Windows Mobile they'll be happy. It will void your warranty however. If you need to send the unit back you can always return it to stock, unless you totally brick it![]()
I guess so.
As for HTC and MS, well, having a cooked ROM voids warranty, and if you brick the phone then tough poop, but if you have a cooked rom and say need to send the phone in under warranty because of a dodgy key, you can always flash back to an official ROM and remove HSPL, send it back, get it repaired, then put HSPL and a cooked ROM on again, lol.
I've been flashing multiple ROMs on all my phones since my XDA Mini S back in 2006.![]()
That's why you flash with USPL, that way it's a lot easier to get back to the standard ROM and pretend you never flashed it (at least from my understanding).

Also HTC/MS have gone on the record as such and said although what XDA do is technically "illegal" (ie breaking the EULA of the software) they also they are turning a blind eye because it is so useful for them and the phone buyers (the chefs etc are technically doing what HTC and MS themselves should be doing).