Its celebration time for LinkedIn as it reaches the mark of 45 Million users yesterday night. The message about this was sent by the Project Manager of LinkedIn, Florina Xhabija, on Twitter.

LinkedIn shared 16 million unique visitors worldwide every month as reported by comScore. In fact, 331 million page views were registered in the month of June which was more than double the amount of visitors in the previous year.

The company was valued at around $1 billion in its last (2008) round of financing, and says they’ve been profitable for 2+ years. LinkedIn has gone through several changes at the CEO role with founder Reid Hoffman changing the guard once again in June of this year after yet another change in December, 2008.

The company is a strong 2010 IPO candidate. Hoffman told us earlier this year “we can go public any time we want to.”