A new job posting (http://jobs.apple.com/index.ajs?BID=1&method=mExternal.showJob&RID=35157&CurrentPage=1) shows that Apple is looking for a cellular technology software manager to manage the cellular protocol software team, responsible for the design, implementation and integration of layer 1-3 protocols for iPhone.
According to Apple, the position will be responsible for ensuring appropriate cellular technology development and execution, KPI performances and interoperability of cellular technology on various platforms, R&D of new protocol and standards, as well as working with cross-functional teams to deliver the best customer experience on cellular. The person hired must have knowledge of: one or more multiple cellular technologies (WCDMA/UMTS, HSPA, HSPA+, LTE etc.)
Apple is apparently ramping plans for advanced 3G and 4G coverage. The job listing may also hint at another US carrier in addition to AT&T either later this year or, more likely, in 2011.