On Thursday, Apple is giving the world a "sneak peek" of iPhone OS 4.0, the newest version of its popular smart phone's operating system. While Steve Jobs & Co. have been typically tight-lipped, the Apple commentariat — just as typically — has whipped itself into a speculative lather, offering these five informed guesses as to what new thrills await:

1. Multitasking
The ability to run more than one app at a time is the most-requested iPhone feature, says Kasper Jade and Prince McLean in AppleInsider. According to "people familiar with Apple's plans," iPhone users will soon be able to run multiple concurrent third-party apps and will have a new screen for switching between them.

2. Wireless syncing
"It's totally ridiculous that iPhones need to be tethered to a computer with a USB cable to sync," says Sascha Segan in PC Magazine. With iPhone 4.0, Apple will "cut the cord" and let people sync their iPhones with iTunes over Wi-Fi, and maybe even remotely over the internet.

3. GPS navigation
All signs point to an integrated GPS navigation system for the iPhone, says Jared Newman at PC World. Apple bought mapping firm Placebase last year, and recently advertised for an engineer to revamp the iPhone Maps program. Now that Google and Nokia offer free GPS tools, Apple has little choice but to follow suit.

4. A unified e-mail inbox option
Currently, the iPhone Mail program locks different accounts into separate inboxes, says Mitch Wagner in Computerworld, but the new OS will reportedly support a "unified mailbox" option — not unlike Apple's desktop Mail app and "just about every other e-mail program in the civilized world."

5. Screen orientation lock
The iPad lets users lock their screens in either a vertical or horizontal orientation, says Kenneth Bruno in Forbes. Look for similar functionality in the new iPhone OS. You may even be able to choose a default orientation for each app, which, "to borrow one of Apple's favorite words," would be "magical."