Actually I heard (directly there in Lancaster) that they are ALL using cell phones. They don't like wires - regular phones are out, but cellular is OK. And they'll ride in cars, but not drive.
That's why my husband (from mid-PA, not Lancaster) says local farms will have Mennonites drive the trucks, while the rest of the work crew will be Amish.
And apparently they deliberate on whether some technology will be OK or bad for them. It's not just blanket "no technology"; they try to discern the effects. Kind of like the misunderstandings (and oversimplification) about Catholics and so on.
I've heard that they'll accept a technology if it doesn't isolate someone from their community & church.
Example - watching TV isolates people from family & community, but maybe they don't feel that cellphones will.
They also believe in bundling - something my parents would hae never allowed.
You're right, at least according to the Wired piece, that it's not a knee-jerk rejection, but a thoughtful process. They've had telephones for many years, but not inside the home, which would encourage people to isolate themselves from the community; the phones are in public areas. In the Wired article, the elders were just starting to consider cell phones, but it was written in 1999, so I guess they've resolved that.