According to ThinkSecret [1], Apple has seeded new builds of Mac OS X Panther 10.3.6 Client/Server (builds 57R28) and Tiger Server (build 8A297).
Tiger Server improves "Directory Services, Failover Service, Gateway Setup, iChat Server, Mail Service, Xgrid, WebDAV, and more" while Mac OS X 10.3.6 builds improvements are not detailed by Apple.