Google continues to encroach on Microsoft's patch, its latest bridgehead directed at the Outlook component of the latter's Office suite.

Launched Thursday and offered for free, Google Calendar enables users to create and send event invitations or reminders via email, also text message via Mobile Phone, and keep track of RSVPs from within the program.

Calendar users can view their schedules by day, week or month; highlight a period for customized view; and selectively display certain events.

The new application reportedly works best with Microsoft Internet Explorer 6.0 and Mozilla's Firefox 1.07 or higher. It utilizes natural language processing plus other smart web programming gimmicks.

And to rub Microsoft's nose well and truly in the doo-doo, Google has also opened Calendar's programming interface to help external developers build compatible third-party programs. Plans are in the offing to synchronize Calendar with Outlook and mobile devices.

All of which lends a hollow ring to the denial by Calendar product manager Carl Sjogreen that the search engine is gunning for Outlook. "We're [just] interested in delivering great products for our users," insists Sjogreen.

Although Sjogreen says Google has no specific plans to insert advertising into Calendar, the potential is clearly enormous if the user-irritation factor can be overcome.

Airlines and travel agencies, for example, would slaver at the opportunity to buy ads next a calendar entry for a company in Manhattan that read: 'Group conference, Hawaii'.

Moreover, many onlookers believe that the calendar bridgehead is one through which the search engine powerhouse can further intrude into Microsoft's backyard.

Last month Google acquired Upstartle, a small company that offers Writely, a web-based word processor that could be used to compete head-on with Microsoft Word. It enables users to share documents instantly and collaborate in real-time; also edit documents from anywhere in the world and store them securely online.

Meantime, Google calendar can be accessed by clicking here.

Data sourced from Wall Street Journal Online; additional content by WARC staff