Possibly, but maybe not. Phone's aren't really designed with GPS navigation in mind. So it may just use a fairly standard GPS system. I've gotten about 7 foot accuracy if I have a very good GPS lock, which meets the less than 3 meter (~9.8 feet) requirement for WAAS. But that might just be a very good GPS lock.
I am a ham radio operator and sometimes its nice to know which location you are specifically in for maidenhead grids - if you are on the border lines in particular (which implies multiple grids at the same time). Some groups want you to use a WAAS GPS to verify you are where you state you are (specifically on the border lines of grids).