There may not be a ton of details about it, but it’s on its way.

Per MacRumors, Apple has released a new build of Snow Leopard to developers, the first since 10.6.7 in March, and potentially the last before the delivery of Mac OS X Lion this summer.

The new build, identified as 10K521, reportedly comes without any detail of changes.

That update was delivered in two flavors, one specifically for Thunderbolt-equipped MacBook Pros identified as build 10J3250, and a general release for other models 10J869.

Mac OS X 10.7 Lion is anticipated to be released at Apple’s Worldwide Developer Conference during the first week of June.

Stay tuned for additional details as they become available.