Danger, whose mobile software powers the Sidekick, a favorite of the Hollywood set, has filed for an initial public offering that could raise as much as $100 million.

The Palo Alto, California-based company has raised more than $100 million in venture capital from traditional VC firms and corporate VC arms.

Aside from entrenched competitors such as Research In Motion, Microsoft, Palm, Nokia, and Apple, Danger faces new challenges with the formation of Google's Open Handset Alliance, which plans to develop an open-source operating system for mobile devices.

Danger's Sidekick models have been spotted in the company of celebrities such as Snoop Dogg and Lindsay Lohan, but perhaps the biggest wave of publicity hit in 2005 after Paris Hilton's device was hacked and its contents laid bare on the Internet.

Danger's revenue climbed to $56.4 million in the year ended September 30, 2007, from $49.3 million in the 2006 period with T-Mobile, its sole wireless carrier, accounting for more than 90 percent. Profits have been elusive. The company had an accumulated deficit of $188.1 million as of September 30.

The company's devices are manufactured by partners Sharp and Motorola, which also owns 11.2 percent of pre-IPO shares.

Other major investors are: Mobius Technology Ventures, 17.6 percent; Redpoint Ventures, 14.8 percent; T-Mobile Venture Fund, 12.6 percent; Softbank Capital, 12.7 percent; Meritech Capital Partners, 7.8 percent; and Venture Strategy Partners, 6.2 percent.

The company, incorporated in 1999, had 923,000 subscribers as of September 30.