The iPhone is known for casual games, but Float might be a little too simple even for most casual gamers. That said, children and those just looking for a super simple experience may find it interesting. It's a game we've all played before -- you get a balloon and try to keep it in the air for as long as possible. In Float, you get a few balloons that fall down the screen towards a row of spikes at the bottom, and it's your job to tap them up and away from the danger below.
It does get a little more frenzied, and there's a bonus area to play with on the lower half, so there is a little strategy in how far you let them drop before batting them back up. But what's really intriguing about this one isn't in the gameplay, it's more in the presentation. The balloons are colorfully rendered, and the UI is very clean and well-designed. There are quite a few game modes, which originally needed to be unlocked via in-app purchase, but are now available for free. There's no Game Center, unfortunately, but OpenFeint is included, as well as a connection to Facebook if you want to share some scores.
Float is available as a universal app for US$0.99, and there's a free version of the app to check out as well. Again, if you're looking for more complicated fare look elsewhere, but who doesn't love batting around balloons anyway?