A major upgrade to Google's Urchin Web analytics server software has finally shipped after a delay of about three-and-a-half years.

Urchin 6, originally due in late 2004, is available for purchase from authorized resellers for $2,995, Google announced Wednesday.

Google acquired Urchin Software in March 2005, and in the next two-and-a-half years placed most of its attention on the company's Web-hosted product, the free Google Analytics.

Unlike Google Analytics, Urchin is designed to be installed on customers' servers, an option some companies prefer for various reasons, such as hosting their data on their premises and not on the vendor's datacenter.

As time passed and Google remained mum on its plans for Urchin 6, customers worried that their investment in the software would go to waste and the product would be discontinued.

After all, Urchin 5.0 shipped in mid-2003, and it had been on version 5.7 since 2005. Prior to Google's acquisition, Urchin Software claimed having more than 20 percent of Fortune 500 companies as clients.

Google broke its silence about Urchin 6 in October of last year, when it announced that the upgrade would enter a beta testing period, dispelling concerns about the product's future.

At the time, Google said it would change the product's packaging by integrating its components, which were priced individually, into a single offering with a flat price.

Previously, Urchin's core piece cost $895 and its optional modules had different prices, including one that cost almost $4,000.

Google will offer Version 6.0 free to any customer who bought a support contract for version 5.0. If customers never bought a support contract, Google will apply whatever amount they paid for their Urchin 5 system toward the price of Version 6.0, which can potentially make it free in some cases.

It's no secret that Google prefers Web-hosted software, and in Wednesday's Urchin 6 announcement, it encouraged users to use Google Analytics.

"We continue to recommend Google Analytics for most users and most circumstances, as its marketing-oriented reports are more advanced than Urchin's. You can even use Google Analytics and Urchin together at the same time and have the best of both worlds," reads the posting on the Official Google Analytics Blog.

Companies use Web analytics software to track, measure and analyze their Web sites' traffic. This information can help a company decide how to modify its site's layout to increase sales, as well as evaluate the effectiveness of online advertising campaigns.

In a related announcement, Google launched as a separate product its Website Optimizer, previously part of its AdWords service. Website Optimizer, which is free, lets site publishers test how effective at engaging visitors different layout designs are. The product has versions in 27 languages.