Not many had the chance to legally touch the new iPhone 3G, besides those that broke the NDA agreement are Laptop Mag and Engadget, and here's some of their notes:

• They got 215kBps on a data speed test on 3G network.
• You can enable/disable 3G, but there is no dual mode.
• Geotagging is built-in.
• The display looks the same.
• It has a thicker feeling due to the round back.
• The plastic doesn't feel cheap, but it's solid, although it will attract many fingerprints.
• The power adaptor, or charger, is a small square.
• There is a separately-sold docking station.
• No mention of clipboard features or MMS.
• Original Apple iPhone are discontinued.

Source: iphone-3g">Laptop via Engadget