(Credit: Apple, Inc.) Apple released on Tuesday new beta versions of the iPhone OS 3.1 firmware and the iPhone SDK 3.1 for developers. The OS 3.1 is available for all versions of the iPod Touch and the iPhone while the SDK 3.1 is available in versions that are compatible with Leopard and Snow Leopard. Without seeing the update we don’t know of the changes it brings, but we’re hoping that it contains bug fixes for problems we’ve covered here and here . If you’ve seen and used this new update please tell us about your experiences with it in the comments. (Credit: Apple)

Like Wolfenstein before it, Id Software’s Doom has been ported to just about every platform known to man. But Doom Resurrection is more than a port: it’s an all-new Doom game written expressly for the iPhone and iPod Touch. Indeed, whereas Id’s Wolfenstein 3D Classic merely shrunk the original down to iPhone size, Doom Resurrection offers eight new Doom 3-inspired levels (six set on Mars, the others in Hell). Screenshots don't do it justice; Doom Resurrection looks tremendous. However, don’t expect a traditional first-person shooter experience; Doom Resurrection runs on rails, meaning you don’t get to roam free throughout each level. Instead, the game moves you from one encounter to the next; the challenge lies in aiming your target reticule (which is controlled by the accelerometer), blasting a familiar assortment of hellspawn, and ducking incoming fire via well-timed taps of the Dodge button. If a zombie manages to grab you, you have to shake your iPhone to get loose before he eats your brains. In other words, Resurrection may look like Doom and sound like Doom, but it doesn’t play like Doom. As it turns out, that’s a good thing. Touch screens and tilt sensors work well for certain types of games, but they’re no substitute for a mouse and keyboard or your garden-variety gamepad. Consequently, in most iPhone-size FPS games, you’re battling the controls at the same time you’re battling demons. That’s a war I don’t care to wage. In Doom Resurrection, however, you get to focus on aiming, reloading, and killing–all with a familiar arsenal of weapons (including the beloved BFG). While longtime Doom fans may feel a bit cheated by the rail system, the gameplay ultimately benefits from it. In fact, Resurrection accomplishes its goal of feeling like a game that was built for the iPhone, not shoehorned into it. Whether or not that justifies the $9.99 price tag is up to you, but I think fans of either the genre or the seminal series will be pleased.

I love free stuff, and it seems like each day brings a wealth of new free goodies to the iPhone App Store. Here’s a look at five notable apps that won’t cost you a cent (at least for now–some are free only temporarily, so get ‘em while you can). This free, sexist app explains the "20! Top Man Things Men Must Know." 20! Top Man Things Men Must Know If you can excuse the sexist, unwieldy title, you’ll find some undeniably useful information here: how to bandage a wound, perform basic CPR, fix a flat, and so on. (Note to developer: Why not call it 20 Top Things Everyone Should Know?) BlueSwap It’s not quite PalmPilot-style beaming, but it’s close. BlueSwap lets you swap contact information with other iPhone/iPod Touch users. Bluetooth makes it possible, meaning there’s no need to use some third-party social network. (I haven’t tried this yet, as I’m the only iPhone owner in the immediate vicinity, so if you’re able to put it to the test, drop a comment.) C.A.R. - Accident Report Nobody likes a fender-bender, but if you absolutely positively must have one, this app will help you manage the details. It’s similar to the iWrecked app I wrote about last month , but a little more robust. Droste Effect This is better seen than described, so I’ll just say that if you like eye candy, you’ll find this one visually tasty app. Really cool. Space Trader: Moon Madness If you like strategy games of the Lemonade Stand variety , which challenge you to make money rather than blast aliens, you’re sure to get a kick out of Space Trader. True to its name, it casts you as a moon-based commodities broker. Buy, sell, profit. Perfect for Ferengi wanna-bes. OK, your turn: What fab freebies have you pulled from the App Store in recent days? Don’t keep ‘em to yourself–let your fellow iPhone users know about them in the comments!