Ok, I see now...which leads me to assume that the state one plans to retire in would matter greatly.

Yes. Since medical insurance laws are set by each state, the state that you live in or plan to live in is a big determinant in your ability to get medical insurance.

Colleges have residency requirements related to in-state tuition.

Assume states would have something like this as well in order to previde border jumping?

Yes, there usually some residency requirements for high risk pool insurance, but they are generally not as stringent as college residency requirements.

For instance, Texas generally requires at least a 12 month residency for to be eligible for resident college tuition: http://info.sos.state.tx.us/pls/pub/readtac$ext.TacPage?sl=R...
but you can establish residency in as little as 30 days for the Texas high risk pool insurance: http://www.txhealthpool.org/eligibil.html

AJ