AT&T has come up with one way to combat the fabled Verizon iPhone: Halve the price of the iPhone 3GS from $99 to $49.

The carrier announced this morning that you’ll be able to pick up the 8-gigabyte iPhone 3GS for $49. (For now, Apple will continue to sell the same unit for $99.) AT&T’s offer is now the cheapest way for consumers to get their hands on an iPhone.

If that’s enough to combat an iPhone on Verizon remains to be seen. Perhaps some users wouldn’t mind going for an older-generation iPhone on AT&T’s notoriously flaky network for such a low price. Then again, many of the consumers who would find a $49 iPhone 3GS appealing probably aren’t too well-versed in the potential advantages of a Verizon iPhone.

Apple is expected to announce a Verizon-compatible version of the iPhone in the next few weeks. I’m currently sitting and waiting for Verizon Wireless’s press conference to begin at the Consumer Electronics Show, where we could potentially hear about the Verizon iPhone as well.