Of my five WWDC predictions posted last week, at least one came true today: Steve Jobs announced a way for third party developers to build applications for the iPhone.

“We have been trying to come up with a solution to expand the capabilities of iPhone by letting developers write great apps for it, and yet keep the iPhone reliable and secure. and we’ve come up with a very sweet solution,” Jobs told the audience gathered at the Moscone Center in San Francisco.

Taking advantage of the fact that the iPhone runs a version of OSX along with full web browser support, developers can create web-based applications which, Jobs claimed, will be able to look and behave just like the applications built into the iPhone. Additionally, Apple will provide web developers with the hooks necessary to access many of the iPhone’s functions including dialing a call, sending email, and integrating with device’s rich client version of Google Maps. Anybody who can write modern standards-based web apps can develop for the iPhone, stressed Jobs.

After debuting first in Asia, and then Europe — this week Nintendo DS users in the USA can finally get their hands on a version of the Opera web browser designed specially for the hand-held game console. Optimized for use with the DS’s dual-screen and touch-screen stylus input, the software comes on a Nintendo DS game card, and transforms the device into a portable web browser which connects through the built-in WiFi.

When I got a chance to test the European edition of the browser earlier this year, I was impressed with the user interface which does make good use of the DS’s unique design. However, similar to my experience with Sony’s PSP, I found browsing to be on the slow side, although whether this is the fault of the built-in WiFi or the time it takes for the device to render web pages, I’m not sure. The other down-side, compared with the PSP, is that because the web browser is stored on a game card, you have to keep swapping it out to actually play games, and then change cards again every time you want to browse the web. It would be much more convenient if the browser came pre-installed in the device’s internal memory. Where the DS browsing experience does trump the PSP though is through having a touch-screen for inputting web addresses on the virtual keyboard. With no touch-screen on the PSP, I found typing to be a miserable experience.

The DS browser has a recommended retail price of $19.99.