Changing text size in a web browser is an accessibility feature. I’ve never seen someone do this besides to read text that is too small. Anyone with sub-par vision needs your site to be accessible. Hell, I do, if I forget my glasses somewhere.

I want to bring it up because major browsers are changing the way they zoom. Opera seems to have started it, and now Firefox 3 does it as well: Modern browsers scale the content wholesale, rather than shifting around font sizes and letting the layout recalculate with the new values.

This is great! Any complex layout requires careful thought to get zooming right: You’re basically designing 3 or more different layouts (the big one, the normal one, the small one). Layout becomes slave to font sizes rather than pixels, the actual medium you’re working in. With the way new web browsers are being made, soon you’ll never do any work to make your site scale. Keep that in mind, watch the progress browsers are making, be ready to stop designing for old-school zooming as soon as it makes sense for you to stop.