I just bought a Samsung SYNC from Cingular yesterday and it works great so far. It has 3G (HSDPA) and Bluetooth 2.0 which makes it a perfect companion for my N800. I haven't speed tested the connection yet, but it seems to be just as fast as using my 10Mbps cable modem. My friend has a HTC Hermes / Cingular 8525 and has speed tested his connection and consistently gets 1Mbps down / 350kbps up. The theoretical maximum for downloading is 3.6Mbps right now, but is supposed to increase to 7.2Mbps later this year although its probably a moot point as Bluetooth 2.0 only supports up to 3.2Mbps I believe. Their 3G service is limited to most metropolitan areas right now, but when you don't have 3G you get their EDGE service which is reasonably fast, 100-150kbps. I'm in the San Francisco area and pretty much get 3G service everywhere. I would look at their coverage map and see what the service is like in your area.

Amazon has the SYNC for -$25.00 after rebates. Unfortunately, I was on a family plan that didn't qualify for Amazon's rebates so I ended up getting it from a Cingular store for $99 - $50 Mail In Rebate. For the data plan I'm using Cingular's MediaMax 200 bundle for $19.99/month which includes 200 text messages, unlimited internet, and unlimited Cingular Video. Technically you are not supposed to tether with this plan, but the concensus on HowardForums is that as long as you aren't abusing bandwidth (i.e. BitTorrent) you'll probably be okay. There is also a new Motorola RAZR with 3G from Cingular that looks like it would be a good phone for data, but I personally don't like the flat keypad and the ergonomics of the RAZR series. Plus, everyone and their mother has a RAZR.

There are a few quirks about the Samsung SYNC that bug me a little. It's supposedly a music phone, but in order to use MP3s as ringtones you have to cut down the length of the track to approximately 25 seconds. My old Nokia 6230 had no problems using full tracks as ringtones. The other thing that bugs me is that you can't turn off the shutter sound when using the camera, and it's quite loud. Supposedly this was done to most of the newer camera phones to prevent people from taking pictures (2.0MP) from taking pictures of people without their knowledge, i.e. bathroom stalls, etc. Other than that I'm pretty happy with the phone. I generally try to find WiFi spots to hop on to, but if I can't find one all I have to do is select my phone from the connection manager and I've got internet access. Hope this helps, and sorry for the long winded post