Several outlets are reporting today that Mac OS 10.5.7 is due to drop any time now. Build 9J47 was released on Friday, less than a week after 9J44, and build 9J50 is said to have been distributed on Tuesday. Until now, these updates have been delivered weekly. This accelerated distribution, along with a shortening list of fixes (the latest build only addresses three) are clues that 10.5.7 is nearly ready.
Additionally, some customers have reported that the ATI Radeon HD 4850-equipped iMacs that they ordered have had their ship dates bumped up to this week (there's a rumor that the graphics card requires 10.5.7).
We'll let you know when this shows up, and report any changes (or problems) we experience after installation.