Originally Posted by Adam 
Can't do much about that, although isn't there a global option on the iPhone to increase webpage font size for certain sites?
Actually no. You can zoom in on any web page you want, but it is not persistant. What you describe might be an option after the upcomming software update this summer.
If you wanted to, and I sure wouldn't blame you if you didn't, you could build an iPhone specific layout. You could then put a bit of code in the header that would automaticly point any visiting iPhone/iPod Touch to that version. It's not as much work as it sounds like. Of douse if you only have a small handfull of people visiting from an iPhone it's probably not worth the hassle. It's not unusable as it is, everything is just a bit small. Some things you need to zoom in on to read.
Come to think of it, if I remember correctly you can put a tag in the page header that will tell Mobile Safari the maximum page width in pixels, effectively forcing everything to upscale. I'll look it up a bit later.