Wheelchairs having priority over all other baggage for the cabins on a plane is not a new rule. Some airlines are so strict about it that they won't even put folding walkers in (between my wheelchair and my walker, I'd far prefer to have my walker in the cabin since it's far less sturdy than the wheelchair, but was not allowed to the one time I've flown with both). The new part regarding wheelchair storage is that they can now store two folding wheelchairs in the cabin with one strapped across a row of seats. I don't really see how they'll be able to do that often since airlines try to really only run full flights when possible, but it's nice to give that option on flights where there are two people with folding manual wheelchairs and the space. I'm sure it helps everyone with getting all the passengers off the plane faster.
ETA: As far as tipping goes, I tip if someone from the assistance company (most airlines/airports actually contract out to a private company) has pushed me the entire way or otherwise gone above and beyond. Depending on service it's been anywhere from $2-10. The $10 was when someone helped me all the way out to a taxi (not just the stand, but to the actual taxi) and if it had been a longer distance or I'd had more than just me and one bag, I'd have tipped more. I usually only have assistance from the gate waiting area to the actual door of the plane (and back up to the gate area on arrival), though, and for that I don't tip since it's short and I'm usually helping with the process anyway.