I've seen this with my ATT Tilt before the mad iPhone 3G rush on the network.Here are the results from testmyiphone:
My issue is the unstable / unreliable 3G connection
Since you can't force users to sync with iTunes, and currently iTunes will not force an upgrade, this would be tough. You will probably see some percentage of users on 2.01 for a long time. (I'd bet most users are still on 2.0.)2.02 actually fixed the speed/reception issue, however because many were scared to upgrade to 2.02 in fear it might break something, they stuck with 2.0/2.01 which makes the network bad for the rest of the 2.02 users.
Apple need to make it unavoidable to install the 2.1 update so everyone upgrades.
They will absolutely do this when the new iTunes comes out. They can't force you to upgrade your phone. They CAN tell you that the only way to use "new features" in iTunes 8 is by upgrading your iPhone to 2.1.I do not see whay Apple could not require all iphones synced with itunes (or when itunes 8 is released) to upgrade to the latest software / firmware.