As reported in detail on MacRumors, Panther update 10.3.8 is now available through Software Update. It weighs in at a hefty 27mb and fixes/optimizes a number of different things across the operating system.
As good sense goes (and by popular recommendation), it’s generally better to wait a day or so after a software update is released to make sure there aren’t a high number of catostrophic issues stemming from said update. So watch the Mac forums (macrumors forums or macosx.com for instance) and rumors sites over the next 24 – 36 hours and if/when all goes well, download to your heart’s content!
About a month ago 10.3.7 was rumored to be the final update before Tiger (10.4) was released. Well, Rumor-freaks can guess a little easier now, as this latest (10.3.8) update or the next are the last possible 2 before Tiger…which won’t bring Tiger any quicker unfortunately.