Two words: Not Plastic
After reading about the dangerous chemicals leaching from plastic baby bottles that are repeatedly heated (via Liz at Mom-101), I went searching for a safe sippy cup. She mentioned SIGG bottles and I found the SIGG Kidz Bottle ($13.56) is a high-tech, aluminum sports bottle for toddlers. Lightweight, tough, and durable, with a twist-and-turn, leak-proof spout and a snap-on bubble cover, the SIGG Kidz Bottle is a safe option for avoiding plastics.
If your little one is still too young for a Sigg, try Evenflo Classic Glass Nurser Bottles (3-Pack) ($6.25).
Updated with two more options:
Thermos Foogo 7-oz. Leak-Proof Sippy Cup with Handle – Blue ($14.99) — When Baby Diva first learned to use her cup, she needed the handles!
Klean Kanteen Sippy Cup 12oz ($17.95)
Updated again: A friend pointed out this report on Snopes. Scroll down for the relevant portion. It discusses the recent report and says that whether or not the amount is actually of concern is debatable and quotes someone suggesting the report may be ideologically motivated. I am personally still concerned and figure it is easy enough to get a non-plastic sippy, but wanted readers to have all the relevant information!