Further to my debunking of alarmism over RFID's privacy implications, here's a nice overview article on pervasive wireless technologies of various sorts, with a realistic take on cost, power, bandwidth and other tradeoffs. Money quote for the RFID issue:
Nevertheless, few enterprises are rushing to attach passive RFID tags to everything. While the tags are cheap, the infrastructure needed to read them and process the information gathered isn't... According to analyst firm IDC, there's currently a bubble in passive RFID. Managers overestimate its usefulness, and privacy activists overstate its Big Brother potential. The greatest driver for passive RFID is a mandate from Wal-Mart that requires its suppliers to attach RFID tags to all incoming shipments by 2005. However, .... the tags are only mandated for cartons and pallets. The individual products on Wal-Mart store shelves will not include RFID tags for the foreseeable future.
The entire article is recommended.