With the misunderstanding about the new gifting option in iTunes, it's wise to read the terms and conditions of the AppStore instead of clicking directly on Accept. Your iTunes account is most likely linked to a credit card and these matter must be treated with attention. Not surprisingly, everything is done as you might have expected: Instead of buying an app for you, you buy it to someone else. You only need to add the email of that person, which doesn't necessarily need to be the iTunes account of the person receiving the gift. It gives the option to add multiple recipients, in which case you will need to pay for the total amount of apps gifted. It remains unclear if this type of purchases counts as a single sale in the AppStore rankings or not. I assume that they're based on unit sold, not in sales.
This can be useful for sending presents in form of iPhone app,... odd? I reckon the best use is for parents to buy apps to their kids from their own account, with no need to have a credit card associated to the iPod Touch of a 12 year old. In my wet dreams I imagine someone using it to spam me with cool applications from the AppStore. Could you imagine checking your e-mails in the morning? At least this is possible now under the new iTunes terms and conditions.