Wow, this is a huge change for 1Ps! Note that this affects the SDC and standby fees.
Those of us on the 1P "bubble" have been stuck with the much-lamented $50 standby and $75 SDC. Finally those days are over ^
Another big change is that UA SDC now allows change of routing when done at the airport! I believe this means we can now officially book connecting flights and change to non-stops.