The patch, called Yahoo Patch Beta 1, applies only to Trillian Pro, the paid version of Cerulean's popular IM client. The company said it plans to offer patches for the older 1.0 version and its free 0.74 software, though it hasn't said when it will do so.
"A patch to resolve the recent Yahoo connectivity issue is currently undergoing beta testing," Cerulean co-founder Scott Werndorfer wrote in an email message. "Once we are confident that the patch is functioning 100 percent, we will update the rest of our product lines."
A Yahoo representative declined to comment.
The software update to Trillian Pro was released days after Yahoo blocked the third-party client from accessing its IM "buddy" lists. Yahoo announced earlier this month that it would require consumers to upgrade to more recent versions of Yahoo Messenger in an effort to stem spam. The Web portal also said it would probably disable access to outside IM providers such as Trillian.
Trillian allows people to combine their chat buddies from various IM services into one master list. IM services such as Yahoo, MSN Messenger and America Online's Instant Messenger lose their distinct features when integrated into Trillian, because it gives them a common look and feel.
The ongoing skirmish between Yahoo and Trillian mirrors earlier conflicts between AOL and Microsoft.
In July 1999, AOL and Microsoft engaged in a similar cat-and-mouse game when MSN Messenger launched with the ability to communicate directly with AIM users. AOL considered the move akin to a hack into its network and blocked MSN from tapping its customers. MSN released software to regain interoperability only to be blocked again by AOL hours later.
Yahoo is not alone in plans to shut out Trillian. In August, Microsoft announced that consumers must upgrade to newer MSN software. Like Yahoo, the software giant said it would likely block out third-party IM services such as Trillian as part of the upgrade.
