Apple made a big deal about allowing in-app transactions with the new iPhone 3.0 API. It's great news if you're a developer looking to make more scratch, but it's potentially terrible news for users.
Basically, this is opening the flood gates for nickel-and-diming microtransactions from the App Store. Before, when you spent $US5 on a game, you knew you were getting the whole game—with free upgrades. Now, you'll spend $US5 on a game and you'll need to spend another $US5 to unlock all the levels and weapons. And that's on legit apps. Just wait for the novelty fart apps with one fart sound that want you to pay for extras, or a flashlight app that wants you to pay for different colours.
This could easily turn tons and tons of apps into crippled trialware without consumers knowing, and it's going to make developers hungry for the extra cash they can make by charging you for extra feature they would have included in the full version anyways. Like a game charging you $US3 for fancy horse armour on the Xbox 360, but without the filter than comes from the huge budgetary requirements of Xbox 360 games, this is going to open the floodgates for the sleaziest app behaviours possible. The worst part of it is, there will be enough people willing to pay a little here and a little there to support this kind of behaviour. But I for one, am out. Do not want. [Gizmodo's iPhone 3.0 Coverage]