It was just yesterday that Apple announced they would allow free apps to enable in-app purchases, and developers are already jumping on the "get the app for free, buy the content later" business model as quickly as they can. ngmoco came out swinging, as Touch Arcade reports, with both a free intro version of Rolando 2 out for purchase, with later chapters of the game as add-ons. They've also been working on a shooter called Eliminate, and we're now told that title will be free as well, with extra content to buy later.

The creators of Urban Rivals, an app that is based on a virtual trading card game, have let us know that they too plan to go the free-with-microtransactions model as soon as their app is released, and though we haven't actually heard from Tapulous, Andrew Lacy told us outright that the only reason Tap Tap Revenge 3 had a 99 cent price tag on it was because of Apple's limitation, so we'll expect that app to go free as soon as it can.

Clearly, there's a drive for this model on the developer side, but the question will be just how much this echoes with consumers -- certainly the "download a trial, buy more later" model has worked well on other platforms, so we can expect it to work here on the App Store as well. But on the other hand, just as when the App Store first opened for business, it's a very "wild west" moment -- everybody and their brother is offering up in-app transactions, and they're all of varying prices and quality.

My guess is that we'll see a few "hits" -- a few free apps that everybody buys content for (Tap Tap Revenge 3 is a good guess; considering that because you know most of those songs, there's much less guessing on what the quality of the transactions will give you). At the same time, there will likely be apps that everyone agrees aren't worth the in-app purchase (it's the old story of "horse armor" when Xbox Live started doing microtransactions). Until we find a good balance, where quality meets price, odds are that it'll be tough for consumers to know just what's worth it, and thus tough for developers to convince them that their content is.

Just in case you haven't yet heard, ngmoco has released Rolando 2 out into the App Store for the premium price of $9.99. The game's subtitled Quest for the Golden Orchid (in this one, you're rescuing a relic rather than a prince), and though it's not cheap by App Store standards, but on the other hand, it's as quality a game as you'll find on the iPhone. We were big fans of the first one, and the second one ups the ante with a brand new 3D look (though still the same great 2D gameplay), and lots more types of Rolandos to roll and jump and fly and drive around the more than 45 new levels. It's fair to say that if you liked the first one, you'll love this one, and if you've never tried rolling a Rolando around, this is a perfect opportunity to start.

There, unfortunately, no lite version of the second game yet, but there is a version of the first one to try, and there are lots of movies to watch over on ngmoco's site, so you can probably get the idea from there. If you're interested in gaming on the iPhone at all, Rolando's on the short list no matter what your tastes are.