Apple has launched the latest version of its mobile operating system, iOS 5.1. So what can iPhone, iPad and iPod touch users expect from the update? Although it may not be a huge step, there are many additions and improvements to the firmware, some of which Apple did not officially announce before the release.

As usual, those iPhone owners running a jailbroken device should avoid the stock iOS 5.1 update until further notice. One of the previously heralded changes in iOS 5.1 is the addition of Japanese support for the Siri personal assistant. So what else has Apple included in iOS 5.1?

The folks over at Tether.com have been working hard to provide their smartphone tethering service over the web, ever since the iTether app was removed from the App Store. Now iPhone users can make their devices into a personal hotspot by simply logging into their tether account via a web browser, with no jailbreak or other iOS software required.

Tethering makes it possible to share your iPhone's data connection with other devices, such as notebook computers. Cellular carriers charge extra for the privilege, although they also increase the amount of monthly data available to the subscriber. Over the years, jailbreak apps have appeared to take advantage of tethering without paying extra monthly fees.

As expected Apple has stopped signing iOS 5.0.1 with the release of iOS 5.1. If you own a jailbroken device you should not update to 5.1 because it breaks both the Corona untether and the Absinthe exploit. The Dev-Team warned both veteran and amateur jailbreakers about the dangers of upgrading on Wednesday.

iPhone 4S and iPad 2 users who did not heed the warning won't be able to downgrade back to 5.0.1 even if they did save their SHSH blobs. People with earlier devices and saved SHSH blobs can downgrade with the assistance of geohot’s limera1n exploit. There is also a tethered jailbreak for non-A5 devices if you really have the urge to get to 5.1.

There's only one thing better than upgrading your iPhone, and that's getting money back for the old one you're replacing. If you're looking to selling the iPhone there are several options available. Totem has established a comprehensive service that streamlines the process and promises competitive pricing.

Simplicity means a lot, because it can take time and effort to post a used iPhone on eBay or Craigslist with no guarantee of payment or pricing. One advantage of HelloTotem.com is a quote up front of exactly what Totem is willing to pay. Accepting the quote puts the process in motion and a pre-paid mailer is sent to your address.

I'm not sure updating to iOS 5.1 is worth losing your untethered jailbreak, but non-A5 users can sacrifice their freedom if they want to. iPhone 4S users should avoid 5.1 if they want to keep their jailbreak. However, non-iPhone 4S owners can keep their devices jailbroken by downloading redsn0w 0.9.10b6. This version is a tethered 5.1 jailbreak for non-A5 devices.

A tethered jailbreak requires that your device is plugged into a computer whenever turned on. Untethered jailbreaks offer the freedom of not using a computer every time your device reboots. Most jailbreakers prefer untethered to tethered. Since iOS 5.1 doesn't offer anything worth losing your untethered jailbreak over I would suggest avoiding it entirely. However, if you are dead set on getting to 5.1 read on for the Dev Team's warning and instructions.