HI,
Boarding passes use 2D bar coding which is difficult to fake. BA are currently trialling this at LHR, BD will start a trial shortly, LH hope to start a larger trial in March 2006 if the TXL trials go well.
I beleive you have a seat selection choice but will most probably not get access to the emergency row or the blocked seats for HONs etc (unless pre-reserved)
Security procedures are being studied to see what needs to be changed to ensure no breach.
Ralph