What’s the story with OS X updates? Seriously, it’s beyond comprehension. This one (10.5.8) only resolves around a dozen bugs and security issues (this or that not displayed right, general stability improvements in specific programs) yet tips the scales at a mammoth 274MB. And this isn’t the first one like that! What could possibly be taking up all that space?
I guarantee it’s not replacing 274MB of code, or even a tenth of that. Is it maybe that OS X is so sewn up into modules that minor issues have to be addressed by replacing the entire library? It’s a bit like curing a cough by removing the head. At any rate, the update has some fixes for bugs that may be bothering you, so get downloading. Or maybe it already is downloading the background, as I have found my Mac does even when I tell it to stop. Creepy, really.
You can get the other updates (server and such) over here.