Last November, Google unveiled its Android software platform for mobile phones and said manufacturers planned to have handsets on the market by the second half of this year.

But phones running the operating system will be delayed until at least the fourth quarter of this year because of problems and concerns among wireless carriers and developers, according to The Wall Street Journal.

Sprint Nextel had planned to launch an Android handset this year, but it won't be able to, the Journal said. One reason is that the Android operating system comes with Google services, and the wireless carrier would prefer to offer its own Sprint-branded features.

Additionally, Sprint may scrap a 3G Android phone in favor of a device that's compatible with its upcoming fourth-generation wireless broadband network.

China Mobile had planned to launch an Android-powered phone in the third quarter, but it will delay the handset until the fourth quarter or early 2009, the Journal said. One hold-up has been the difficulty in translating the Roman characters in the Android software into Chinese.

Developers have reportedly had trouble with the open source platform as well, especially compared with Android's well-established rivals.

Apple's iPhone soon will have an application store that will enable entertainment, online retail, and business applications. Some developers suggest Apple's mobile platform is easier to develop for because of familiarity with the Mac OS X operating system. Apple also has the advantage of control over the hardware for its mobile platform, while Android is designed for a multitude of hardware, software, and providers.

Despite these issues, Google appears to be highly interested in the mobile market. CEO Eric Schmidt recently said he expects the mobile market to ultimately have the highest advertising rates.