Both AppleInsider and independent MacRumors sources claim that Apple has seeded the first builds of 10.4.1 to developers. The build is said to fix more than 20 bugs already reported to Apple regarding various software and hardware incompatabilities with Tiger. Key issues regarding stability and reliability of the OS as a whole are the focus, along with user issues with certain D-link networking equipment.
According to the rumor site, the forthcoming update is expected to be released mid to late-May.