Apple’s new iPhone 3G S has barely hit store shelves but already there’s talk of next year’s models, which are expected to leverage ARM’s multi-core processor designs in giving the touchscreen handset a significant performance boost while simultaneously increasing battery life once again.

Like Palm’s new Pre device, the iPhone 3G S is believed to be powered by a single-core ARM Cortex-A8 running at roughly 600MHz. It may be the last of its breed, however. Future embedded processors from the world’s leading mobile chip designer are expected to follow a path similar to those for conventional PCs, by which performance gains are achieved by scaling up the number of available processor cores.

Reference designs for ARM’s next-generation Cortex-A9 call for versions with either two or four cores, with dual-core versions “definitely” slated to turn up in smartphones that will ship sometime in 2010, James Bruce, wireless segment manager for ARM, told CNet News.com in a phone interview earlier this week.

“What we’ve done on the A9 is actually make it more power efficient than the A8,” he said. “The dual-core A9 will be coming out on 45-nanometer rather than the (current) 65-nanometer process.”

The smaller, more precise design of the A9 will signal a faster, more power-efficient chip. And although power consumption will increase some 10 to 20 percent at peak performance when compared to the A8, Bruce noted that smartphones based off the new design will actually see better battery life in real-world usage situations.