Current devices will not be upgradable to WP8.

[DavidinCT]

You will get a update to 7.8 that will give you the tile interface like WP8 has but, due to the MAJOR changes in Windows Phone 8 current devices could not handle it. The only changes in the 7.8 update is the updated tiles, nothing else.

Yes, WP8 is going dual core !

Microsoft unveils Windows Phone 7.8 update for current hardware | wpcentral | Windows Phone News, Forums, and Reviews

It's a good and bad thing. If you were an early adopter(GSM models on release), your 2 year should be up in fall (on release time). If your with Sprint or Verizon, well, late spring/early summer 2013 for(if you got it on release) your 2 year to be up.

If you like WP7, read up on WP8, with true hardware access, direct C/C++ support, it's going to be an awsome gaming machine. Everything WP7 should of been.

I did watch the 2 and 1/2 hour Windows Phone 8 press statement today... It's inpressive. Not sold on the new tile layout but, I think it will grow on me.

If you just got a new 2nd gen unit(lumia 900/Titan 2), I'd be a little upset too....