Despite hopes for an imminent release, it appears Mac OS X 10.5.2 is not yet ready for public consumption. Last week, Apple released a couple of seeds with "no known issues", but apparently has continued to work on the latest Leopard release.
Today, Apple provided developers with the 9C27 and the seed notes indicate that there are still no known issues.
Apple released the first Mac OS X 10.5 update (10.5.1) only 3 weeks after Leopard's initial launch. 10.5.2 has been particularly anticipated as it introduces a some interface changes along with the usual bug fixes.
Of note, the just-released MacBook Air ships with a version of Mac OS X 10.5.1.
Update: No known issues in the latest seed.