Mr RFID makes a prediction:

Debate all you want - I predict UHF (Ultra-High Frequency) RFID will be used at the item level in the global supply chain.

I've heard the arguments; UHF RFID does not work with metal and liquids. It's true; there are challenges, but experience teaches us how to work around those challenges and companies are making huge improvements in UHF based products to help.

Now, before you call me a HF (High Frequency) bigot, I want to go on record saying that I have actually deployed more HF readers than UHF readers; but during the past six years, I have implemented many systems that use UHF with metal and water based products. The solutions used a couple commonly known tricks of the trade.

Another interesting bit of insight from Lou Sirico, aka Mr. RFID.