Typing on the iPhone or iPad becomes easier as you get used to it, but some things remain cumbersome to write even after years of use. The keyboard acrobatics required to type something like "Wi-Fi + 3G" or a long email address on a touchscreen keyboard can be somewhat maddening if you have to input that multiple times a day.
Fortunately, a new feature in iOS 5 comes to the rescue: custom keyboard shortcuts. In the Settings app, navigating to General > Keyboard > Shortcuts gives you access to a fully customizable list of shortcuts you can edit to your heart's content. If you're familiar with TextExpander on the Mac, this setting in iOS 5 functions much the same way.
Only one shortcut is included by default: "omw" = "On my way!" You can edit that shortcut or add completely new ones, and as long as the shortcuts are easy to remember and easy to type, you can vastly speed up your typing on the iPhone for common phrases you use.
When you tap the "+" icon on the Shortcuts screen, you'll see a page that gives you input options for "Phrase" and "Shortcut." The "Phrase" setting is what you want your shortcut to expand into, while "Shortcut" is what you'll actually type. As one example, I've set up "Wi-Fi + 3G" as a phrase on my iPhone. All I actually have to type is wifiggg, and my iPhone will automatically expand that into "Wi-Fi + 3G."
I also write about Apple on Twitter quite a bit, and in order to squeeze within Twitter's character limits I've set up a shortcut to substitute in the character for the Apple logo () whenever I type the shortcut applogo. Setting up similar shortcuts will allow you to type all sorts of special characters not included on the iPhone's keyboard.
Another way the keyboard shortcuts feature comes in handy is circumventing the standard autocorrect for some terms. Many times in the past I'd type the word "hell" and have it autocorrected to "he'll," for example (all those times my mom put soap in my mouth didn't teach me a thing). I still haven't been able to work around what I consider iOS's most irritating autocorrection -- its always corrects to it's even after setting up a keyboard shortcut trying to prevent it -- but I've been able to eliminate most iOS autocorrect oddities via keyboard shortcuts.
iOS 5's shortcuts feature is a great way to simplify inputting text you find yourself typing many times throughout the day, and as PC World points out, you can even use it to set up multiple email signatures for different use cases. As far as I can tell there doesn't appear to be a limit to the phrase length -- I put in half the lyrics to "Yellow Submarine" with a "yllwsub" shortcut, and iOS didn't complain -- so you could potentially create shortcuts for several paragraphs of text that you can quickly input with just a few keystrokes.