Now...
...just wait. Remember the earlier Security Update when everyone freaked out because they assumed Apple wasn't going to release a fix for Jaguar. And then they did.
Apple does cater to its flavor-of-the-year OS first, but it has in many instances updated the older versions. I'm not guaranteeing they will here, but since it involves updating webpack it may take more time for Jaguar.
For those who are still using Jaguar, Panther's better and worth the 120. Furthermore, I'd rather have the choice to update than have a constant monthly bill for my OS. I don't mind paying 120 every 18 months or so if the OS includes new applications, utilities, and stability in a neat package.
For my 120, I received File Vault, Expose, iChat AV, labels, etc. Plus a new finder, etc. And Panther made my old 233 iMac work faster than it had under Jaguar. I actually use it now.