As far as 121 goes, I'm pretty sure privately owned iPads are a no-no if there is no OpSpecs approvals for a EFB at a company. You can still bring your iPad on trips and all - for personal use, and what happens up front stays up front between crewmembers, but don't let any check airmen or FAA reps catch you using it during a flight when you should be referring to a company manual/approach chart.
It is so nice to pull up dispatch releases, find out if there's jumpseaters waiting to get on the flight that we need to be holding for, and as well as getting rid of 30lbs of paper.