Google negotiators this weekend continue to hammer out agreements with wireless carriers, handset makers, software developers, and hardware providers, as the company prepares to announce on Monday an ambitious platform for creating mobile applications.

Although Google has declined to comment for months on its rumored move into the mobile space, sources said the company will make an announcement Monday at 11 a.m. ET, and that details of the plan are being finalized this weekend.

Google will announce an open source development platform for mobile applications that will contain a full set of components, including an operating system, a set of common APIs, a middleware layer, a customizable user interface and even a mobile browser, sources said. Instant messaging standard protocols will also be supported.

The platform is intended to simplify the process of creating and deploying mobile applications, so that an application can be built once and be compatible with multiple phones.

On the partner side, well over 30 industry heavyweights are already on board, including Intel, Qualcomm, Broadcom, Nvidia, Sprint Nextel, T-Mobile, China Mobile, Telefonica, NTT DoCoMo, LG Electronics, and HTC, the sources said.

With negotiations expected to continue through the weekend and into Monday morning, it's possible that the list could exceed 40 partners. Among those not supporting the announcement at press time are Nokia, Verizon, and Apple.

The development platform will be freely available to anyone who wants to use it, and, aside from a common core, will provide a lot of flexibility for modifications and extensions.

The ultimate goal is to lower the costs and simplify the creation of mobile applications and spur innovation that, as Google sees it, has been hampered by technical fragmentation. As such, the Google offering will rival existing mobile platforms from Microsoft and Symbian.

For Google, the benefit will come indirectly from an acceleration in improvements to mobile phone interfaces, which the company reasons will make it easier for people to access online services, like search engines, and applications, from their mobile phones. The intent is to bridge the gap between the Internet and mobile phones.

As usage of Google online services increases on mobile devices, so will the advertising revenue the company generates.

Mobile advertising is a tiny market but is expected to grow quickly in coming years. According to Opus Research, mobile advertising spending in North America and Western Europe will reach a combined $5.08 billion by 2012, up from an estimated $106.8 million at the end of this year. This represents a compound annual growth rate (CAGR) of 116 percent.

Opus Research, which released the forecast last week, said that improving the mobile user experience will drive ad revenue growth, which will prompt more people to spend more time using the Internet via their cell phones.

In addition to Google, all other major providers of online services, like AOL, Yahoo, and Microsoft, are busy tweaking their Web sites and Web applications for use via mobile phones.

As the Google deal takes its final shape, it appears more and more likely that it might pit Google against its traditional ally Apple, and align it with carriers that have been hurt by the success of the iPhone.

Although the platform will be available to anyone, including Apple, it could indirectly accelerate the pace at which competing handsets catch up with the iPhone's user experience innovations.

A few weeks ago, Apple announced it will release a software development kit so that third-party developers can build applications for the iPhone. It expects to make it available in February.

If Apple is absent from the partner list in Monday's announcement, it could signal that Steve Jobs's company views the Google platform as a negative development in the mobile market, an interesting situation, considering Google's CEO Eric Schmidt sits on Apple's board.

The intensity of this weekend's negotiations is not surprising, but rather reflective of the bold undertaking Google has assumed in the notoriously complicated world of dealmaking in the wireless market.

As has been reported previously, the components of the Google platform will not be delivered until at least mid-2008. At some point, the effort might even yield a Google-branded phone, sources said.