iPhone users today are patiently awaiting the release of iOS4, Apple’s latest version of the iPhone operating system. The planned release of iOS4 comes just as Apple prepares for launch of the iPhone 4 on Thursday. As of 10 a.m. Central time, iTunes had yet to make the firmware update available for download.

The latest version of the OS was unveiled at an April Apple media event in San Francisco. iOS4 includes multitasking, a new folders system for organizing apps on the iPhone, enhanced mail features, iBooks for iPhone, upgrades to Apple’s enterprise software, a social gaming network called Game Center and an advertisement service called iAd.

Apple is still reeling after June 15 pre-orders for the iPhone 4 blew past projected demand for the devices. Apple and AT&T reported more than 600,000 per-orders, which generated high Web traffic that shut down AT&T’s website for most of that day. The phones are now on backorder and Apple is reporting an early to mid-July ship date for second and third batches of the iPhone 4.

Check back with Wireless Week later today for a look at the new OS.