Can they? Not at the moment - they are in the realm of science fiction.
Could they be an efficient form of transportation? That's another story. I'm going to say no.
Assuming that the cost of teleportation could be kept around the price of airfare or lower, it would put the airline, railroad, and shipping industries out of business. If it were competitive with local transportation options, it would kill commuter railand the taxicab companies. It might not end up being that efficient, though - long lines at airport security and packed subway trains would be replaced by long lines at teleport stations.
Time travel would be even more of a hassle. If you think the current economic recession is bad, just imagine what would happen if hedge fund managers suddenly had the ability to jump into the future to see how stocks and commodities were going to perform - or could jump into the past to try and correct an earlier bad investment? Lotteries and gambling would become meaningless, sportscasters and weather forecasters could just pre-tape their segments for the year, insurance companies would refuse to cover patients and drivers based on their future accidents and illnesses. People arguing on the Internet would no longer merely be editing Wikipedia to prove their points, but jumping back to change history. Not to mention all the universe-destroying paradoxes.
No thanks - gimme old-fashioned locomotion and chronology any day.