Go to Testmyiphone.com - iPhone Speed Test from your iPhone, and test it out. Post your results here. Consider it a friendly competition between fellow iPhone owners...
Here are some test I took the other day. This is kind of the low range I get while sitting in front of my computer, but it changes every second so if I did a test right after that it could have been higher
depends where i stand in my house. Certain spots in the house recieve no 3G. But when i stand other side of the room it will be quite fast. Not tested the speed but i will try out that app tonight
There's a good chance that because its a new network, everyone is trying it out at once, which can reduce the speed. Also, at&t's 3g network is just rather moody, no two ways about it. At its fastest, it will smoke EV-DO, but it doesn't seem to hold as consistent of a speed as Verizon's network, at least in my experience.
At my home in Frederick, MD (speedtest.net app, 45 miles north of DC)
~1000kbps down
~250kbps up
In Washington, DC
~2000kbps down
~300kbps up
3G was just expanded to my home in Frederick in December. I found downloads to be quite a bit faster in DC and I assume they are probably similar in Baltimore as well. But even 1000kbps is pretty fast I think for a wireless cell service. It also varies a bit naturally, but looking at my testing results those are the averages. I also tested EDGE one time at home, it was pretty bad; ~150kbps/~80kbps. But I think my area is one of the ones where EDGE was down graded for better 3G.