Trillian users rejoice: Cerulean Studios has concluded its lengthy beta period today and Trillian 5 has emerged with a new interface, additional features and a fresh business model. Entering public beta last August, the latest version brings a resizable, ribbon-inspired interface with Windows theme integration, new icons for services, and cloud-based chat history. The messenger has also gained new social features, including Facebook, Twitter, and LinkedIn integration, as well as a Foursquare plugin with GPS support.

The latest build also represents a significant change in the way Cerulean will profit from the software. Founded in 1998, the developer initially offered a free version of Trillian and was funded solely through user donations. That changed in 2002 with the introduction of Trillian Pro, a commercial version of the instant messenger that cost $25 per year for additional features. Cerulean later abandoned its subscription model, allowing users buy a $25 license that covered the entire life of a Pro build (all of 3.x or 4.x for instance).

Cerulean has decided switch back to a yearly subscription, offering a single free version of Trillian with the full functionality. The catch, of course, is that the software is now supported through advertisements from Netflix and other services. To disable the ads, you'll have to subscribe to the new Pro service, which costs $12 per year. The Pro service also allows you to store your chat logs in the cloud, protecting them against hardware failure -- though with all the security breaches lately, this makes us a bit uneasy.

Before announcing this plan, Cerulean allowed users to purchase a commercial license for Trillian 5. Those folks will be grandfathered into the new scheme. According to the company's blog post, if you paid for the latest version, you will receive the new Pro service for the lifetime of Trillian 5.x -- not just a year. Although many old school Pro users are angry about the change, most seem confused about the new terms, thinking they'll eventually have to pay a $12 subscription fee for Trillian 5 on top of the previous $25 license fee.