Apple have released OS 4.2 for both the iPhone and the iPad. To install simply plug in your device, load iTunes and check for updates. This new version of the OS comes in at 624.3MB in size so a pretty hefty update.
The main update in this OS is for iPad owners who now get access to Multitasking and Folders which iPhone customers have had for a while now but you also now get AirPlay for streaming your content to a TV via Apple TV, you also get AirPrint which allows you to finally print your documents over a wireless connection.
For a full list of all the updates check out the link below
Link – Apple iOS 4.2