Google has dropped Trillian from its Google Pack software suite with nary an explanation, prompting a terse reaction from Cerulean Studios, maker of the popular instant messaging application.

"Our goals are seemingly no longer perfectly aligned with those of Google. Their reasons for removing Trillian are their own and were not made available to us," wrote Scott Werndorfer, Cerulean Studios' co-founder and head developer, in the company's blog on Friday. "We harbor no ill-will towards them and wish them the best of luck; they're going to need it."

Reached via e-mail, Werndorfer declined to comment further. Meanwhile, a Google spokeswoman confirmed Trillian's removal from the Google software collection. "Google Pack is currently in beta, and the selection of software available through the Pack will continue to evolve," she wrote via e-mail. Neither company could clarify exactly when Trillian disappeared from Google Pack.

Trillian had been a part of Google Pack since the suite's introduction in January 2006. Google Pack, which can be downloaded for free from Google's Web site, includes products from Google and other vendors, including Adobe Systems, Mozilla and Symantec.

Google has said in the past that the applications in Pack are ones that it deems useful, that enhance users' online and desktop activities, such as Web surfing and communications, and that don't violate certain Google principles.

"Every program included in the Google Pack is free, has earned a reputation for excellence, and was evaluated to ensure it meets Google's Software Principles. Google respects users' rights to control their own computers and does not include software that is spyware, generates pop-ups, or that is difficult to uninstall," Google said in the press release announcing Google Pack.

The exclusion from Google Pack comes at a critical time for Cerulean Studios, which is gearing up for the release of Trillian's newest upgrade. Code-named "Astra," this new version of Trillian is now in beta testing, but when it's ready later this year it will not benefit from Google Pack's distribution muscle. Once Google Pack is downloaded, Google automatically maintains and updates the applications on users' machines.

Trillian has been popular for years because it consolidates in a single interface IM contacts from a variety of IM services, such as America Online's AIM, Yahoo's Yahoo Messenger and Microsoft's MSN Messenger.

Many users find this extremely useful. Most IM services don't interoperate with each other, making it necessary to log on separately to each IM network to communicate with its members. While Trillian doesn't solve the interoperability problem, it does prevent users from having to keep an IM buddy-list interface open for each network.

The press release announcing Google Pack contained the following comment from Werndorfer: "We're very excited for Trillian to be included in Google Pack, as we at Cerulean Studios have always been very focused on giving end-users the highest quality experience possible. We believe this goal aligns Trillian perfectly with Google Pack."