On one front, Yahoo is introducing a new tool that can synchronize address lists between social networks and Apple's iPhone. But maybe more importantly, a new Yahoo SDK may enable this and other apps to find their way to Symbian and WM6.

Extending its battlefront against Google to the mobile playing field, Yahoo this week rolled out plans to build its own applications for Apple's iPhone, as well as to produce new tools for outside developers that will enable their applications to migrate more easily among various smartphone environments.

Specifically, Yahoo's goal is to enable a single application to work across Windows Mobile, Java, and Symbian environments without extensive recoding...and iPhone could also play a role. Possibly to that end, Yahoo also announced its first application for the iPhone and iPod Touch, which we could eventually see ported to Windows Mobile and elsewhere by way of Yahoo's new developers' tools.

Yahoo's oneConnect will be a "social address" solution that combines contact lists from cell phones with contact lists on social networks, under a single interface.

The company has also said it is using its own developers' tools internally to build oneConnect and its other iPhone apps, so it wouldn't be all that surprising to see Yahoo port the new OneConnect to other devices beyond the iPhone and iPod. Yahoo is offering these tools as runtimes for Blueprint, a mobile SDK previously used for producing widgets for the Yahoo Go mobile service.

Yahoo's new Blueprint Runtime for Mobile Sites "creates a proxy layer that redirects HTTP requests from your server to Yahoo's," said mobile project manager Markus Spiering on the Yahoo developers' site. "This allows you to 'host' the Blueprint service on your own server while relying on Yahoo's back end to interpret and render Blueprint markup, giving you the right HTML or xHTML that looks best on your users' phones." The new Yahoo Blueprint Runtime for Mobile Apps, on the other hand, gives the developer "full control over how and where to distribute" standalone mobile applications, Spiering added. "The full version will provide you with the possibility to create mobile applications across a wide range of Java, Symbian, and Windows Mobile devices." Preview versions of both runtimes are now available for free download from the developers' site.

To help boost the use of Blueprint among outside developers, Yahoo is teaming with M.Net, Netbiscuits, and Crisp Wireless -- three Web development firms that have agreed to give their customers the option of getting their mobile Web applications built with Blueprint.

Under metrics used by market research companies such as comScore, Google holds a commanding lead over Yahoo in the overall search engine/ad space, although Yahoo ranks ahead of Microsoft -- a company that tried unsuccessfully to buy Yahoo earlier this year -- and fourth-place competitor AOL.