Adobe has reported today that it will purchase Omniture, an online marketing and web analytics company, for some $1.8 billion (or $21.50 per share -- a 45% premium). This acquisition is Adobe's largest since buying Macromedia for over $3 billion in April 2005, and it plays a part in the company's attempt to expand its presence in the business software arena.

According to Adobe CEO Shantanu Narayen, the purchase is a "game changer." With Omniture's scalable SaaS platform, which captures over a trillion transactions per quarter, and other additions, Adobe will enhance its offerings and appeal to online marketers.

Meanwhile, Omniture will become a new business unit within Adobe, and its CEO, Josh James, will sit as senior vice president. The analytics firm will benefit from Adobe's large global operation and the ability to more quickly penetrate new geographies and markets.

The deal is expected to close in Adobe's fourth fiscal quarter and is subject to government approval.