It's not quite a hostile attack yet, but yesterday, Carl Icahn and the funds that he runs announced that they would try to get elected to three seats on the board of directors at Biogen Idec (Nasdaq: BIIB).

Icahn has been heavily involved with Biogen since he tried to publicly engineer a sale of the biopharma after acquiring nearly 9 million shares of Biogen stock. When Biogen announced that it couldn't find a buyer in December, shares promptly fell 24% ... which probably irked Mr. Icahn.

After failing to find that deep-pocketed acquirer -- and believing that this failure was partly the fault of sandbagging by Biogen management -- Icahn was apparently spurred into action yesterday by weekend news reports that Biogen might do its own "large scale," or up to "$10 billion," acquisition of a European biotech company.

Now that Icahn is starting to tire of Biogen's management (you can see all his complaints on page three, here), he has decided to nominate three of his associates for the four open seats on Biogen's 12-person board of directors at Biogen's annual meeting later this year.

Even if all three of Icahn's board nominees get elected, he still won't have a controlling share of the board this year, thanks to Biogen's staggered annual board elections process. To ensure that he could take control of the board in 2009 if "Biogen's management failed to act to enhance shareholder value" this year, Icahn is also seeking to freeze the size of the board at 12 seats.

So will having Icahn and his cronies on Biogen's board be a hindrance or a net positive for Biogen investors? In the past, Icahn's influence has been mostly beneficial to shareholders of the drugmakers he's worked with. Last year, he apparently helped to engineer a sale of MedImmune to AstraZeneca (NYSE: AZN), and definitely not at a discount price.

Icahn is also well-known for his involvement in ImClone Systems (Nasdaq: IMCL). Shares have been up significantly since Icahn took a more active role, ousting the drugmaker's former management back in late 2006. Most of the credit for the turnaround in ImClone's fortunes doesn't belong to Icahn, though. It resulted from what traditionally causes biotechs to rise and fall; namely, positive clinical trial data with its lead drug, and negative clinical trial data for competitors' drugs.

Although Icahn's presence could be either a net positive or a net negative for Biogen investors, he's sure to make things interesting over the coming year, especially if Biogen fails to perform to his expectations. Expect 2008 to be just as much a roller coaster for Biogen as 2007 was.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool's disclosure policy was elected to the documents board of directors, but never went to any meetings.