Here at EWR and I'm sure at every other US international airport these "passport readers" are used at check-in for immigration purposes. Its a way for them to keep track of nationals and residents.
I remember that the US Immigration Service scanned my Passport when I arrived in SFO. But I dont know what Informations they can see on their Monitors.
All passports have 2 lines at the bottom of the name page which is the information for the reader.
My Russian Visa has those lines too, but i doubt that they have that system at all border-crossing stations...