You have to look at the big picture as to why there are penalties for moving.
Usually it is because you've got a "deal" or preferred rate on your mortgage which is in place for a certain nnumber of years.
If you leave before that number of years is up then they won't have made back any money on you, so they add in a panalty clause.
It is the same for general extra repayments, many mortgages will only allow you to make a few extra payments during the term without penalty.
We're currently in the process of moving our mortgage from The Halifax to The Cambridge building society.
If the mortgage goes through on or before 1-5-07 then we would have to pay a £1100 early redemption penalty.
If we wait until the 2-5-07 then the only fee from The Halifax is a £100 admin fee (which The Cambridge are picking up for us, along with all their own fees) so it won't actually cost us anything to move.
We will be locked into the new mortgage with The Cambridge for 2 years, however their Early Redemption fee is only actually £60 at any stage - so we could move away from them very easily and for very little money.
However as we're getting a good deal from The Cambridge (building societies do seem to offer good rates and we are already members of the society through virtue of a savings account) I doubt we will be wanting to move on for a while anyway.