This all too complicated for me...!
How does this rebanding affect me listening to the Mass State Police? I have heard many of their frequencies won't change...

Alright if we take Zone 5 as it sits today for an example...  5:00pm  9/29/05

Now none of these frequencies above are located in the portion of the 800MHz band where the actual frequencies would shift after rebanding.  So with a quick look at the rebanding issue you might think if all you cared about was the MSP trunk that you where all set... Well you would be wrong. You see the problem is that your scanner and Motorola radios don't use the Frequency information when decoding the data on the control channel. They instead use the FCC channel numbers and then through a table calculate the actual frequencies. As you can see from the chart above though the frequencies in Zone 5 aren't changing the channel numbers are. And when this change takes place older units will be tuning to the wrong frequency with the new channel numbers in the data streams. For an example after rebanding  without a firmware flash or a table update your scanner may get the info to follow a conversation to ch459 which then would be 859.7125 but your scanner would try and tune to 862.4625 the old home of ch459.
Now I did ask Paul Opitz from Uniden if the older non control channel scanners would be affected since you enter all the frequencies manually. He however wrote me back and told me that they still use the channel numbers to inititally decode the data and would still be quite lost.
So there is the rub....

Resource to check it out yourself:
The complete before rebanding and after rebanding channel list
How this affects Motorola Radios