So there was some question as to whether or not tether apps would work on the DX. It was previously reported that an app I've never used works. I'm VERY happy to report that PdaNet does indeed work on the DX. I'm pulling ~1-1.25mbps down and ~0.45mbps up. Not the greatest, but works for me.
Also, I was able to pull over 8mbps down and 2.5mbps up with my DX connected to a wifi network, so it's good to know that the phone can handle those sorts of bandwidths just fine.