well the actual phone itself hasn't change that much,
thinner, yes, only around the edges though.
It has 3G and GPS (turn by turn) in it.
the headphone jack is universal now, in which it allows for any headphone to be used. All black metal casing, and white available in the 16G.
apart from that, the big differences are going to be viewed in the interface of the phone. but the 2.0 can also be downloaded to the current gen iPhone, that's why i don't really see the need to upgrade, for me at least.
they focused more on the Apps to make it more viable in the business market. expanded the use to more countries, and made it cheaper, but where they get you is in the two year contract with all the bells and whistles.
that's why i'll just stick to my hacked iphone with T-mobile, whom i've been with for around 4 years now. I only pay around $30 a month, and i use wi-fi for all my browsing needs. Wi-fi can be found anywhere now a days and it's faster than 3G. all the Apps, which are a big deal for the for the next Iphone, can already be had with third party apps running on hacked iphones. except that now they are going to charge you. around 10 bucks per app. so yeah.
No new Camera 5Mp (even if they made it a bit thicker to fit this in, i wouldn't care.
NO bigger FlashDrive ("")
no video conferencing. If you are going to have 3G, this would have been a no brainer.