There's a key post on calculating the real value of your tracker - run a search on aam for it.
As regards deals being done, I doubt it - there have been plenty of reports of people approaching their bank (including myself) but no report of success. Of course there may be isolated instances of deals having been done - but IF they do exist, they must be exactly that i.e. isolated.
The only deal that was ever offered officially was the one PTSB offered a couple of years back. From what I could gather at the time of it being discussed here, their offer didn't come near the real value of their customers' tracker mortgages.
Personally, I'm planning on keeping cash on account - and ultimately using it - rather than paying off the tracker. It's the cheapest financing I will ever get - so plan on going the full term with it without any overpayments.