It's expected to be the biggest IPO since Google in 2004:

The social network for business professionals this morning increased the price range for its highly-anticipated offering by 31%, meaning that it now expects to be valued at more than $4 billion.
The Mountain View, Calif.-based company originally filed for its IPO in late January, with plans to raise $175 million. It upped the ante earlier this month, setting its terms to 7.84 million shares being offered at between $32 and $35 a piece. That would have meant a $274 million raise at the high end of its range, and an initial market cap of just over $3 billion. Now, the range has jumped to between $42 and $45 per share.

Hopefully one of their revenue models is a service with which one can opt out of receiving their e-mails. I'd pay for that.

Via CNN