The Wall Street Journal (WSJ) reports that Apple is facing competition from software developers that plan to open up rival online stores that allow users to download unauthorised applications to their iPhones. The report cites services – such as Cydia Store and Rock your Phone – that could potentially sell hundreds of iPhone applications that are not available through Apple’s official store. The WSJ report notes that the upstart sites can carry software programs that Apple’s official store won’t, since Apple tightly controls the kinds of applications it allows. The App Store rejects some submissions, for technical and content reasons. Despite this, the App Store has been a huge success, with customers already having downloaded more than 500 million applications.

Meanwhile RIM this week unveiled its own application store – BlackBerry App World – as well as pricing guidelines for applications that will be offered through the store. ZDNet notes that the store, due to go live this month, provides a place for third-party developers to sell applications they have created for BlackBerry smartphones. According to the North American version of the developer page for BlackBerry App World, there will be nine tiers of pricing for applications, ranging from free to £8.55 per application. After free apps, the cheapest application price will be £2.59. BlackBerry App World is RIM’s answer to Apple’s iPhone App Store, Google’s Android Market and Palm’s Software Store. At the Mobile World Congress last month, Nokia announced it will introduce its Ovi Store, and Microsoft said it is preparing its Windows Mobile Marketplace.