Billionaire activist investor Carl Icahn says he is suing Motorola (NYSE: MOT) to compel the company to hand over documents related to its mobile device business. He is also, not surprisingly, urging investors to support his slate of nominees for the company's board of directors.

In a letter to shareholders filed with the SEC Icahn wrote that "As we all are painfully aware, over the past 18 months, the market value of Motorola has dropped by over $37 billion. More than $17 per share of Stockholder capital has vanished under the "guidance" and "leadership" of the current Board ... "

To correct the problems at Motorola, Icahn said that two things were necessary: spinning off the mobile device business and giving shareholders a "strong and capable voice in the boardroom." He also included a detailed list of "Empty Promises: Motorola's Record of Failed Leadership." If you're interested in Motorola at all, you absolutely must read this letter.

Icahn's battle for control of the company's board and removal of CEO Ed Zander failed last year, although Zander was subsequently pushed out after more bad results. Now Icahn is raising questions about recently-installed CEO Greg Brown:

And what "qualified" Brown to be the CEO? He certainly - as far as I can ascertain - has no in-depth experience or knowledge concerning the Mobile Devices business, which was and is by far the major problem for Motorola. Hopefully, our litigation with Motorola will soon reveal just how hard our "blue-ribbon board" tried to find an alternative to the "qualified" Mr. Brown.

Classic Icahn. Priceless. Icahn controls 6.4% of the company's stock and, given the continued failure of the company to generate value, his second battle for control of Motorola should draw more support.