Thanks for your note. I went through this same hassle when I added a favicon.ico to some of my sites after having them up and live for months on end. The basic problem is that browsers cache the favicons and never seem to check if the site has a new icon (or has gone from a generic or missing icon to one that's actually specified).

The easiest way to try and fix things is to choose "Empty Cache..." from the Safari menu in Apple's Safari browser, but it's pretty unlikely that'll work because, well, it's just too darn easy. Fortunately, I've already addressed this issue with Safari in two related articles: selectively removing Safari favicons from your cache and Why doesn't Safari show me favicons?. Read those two, they'll show you how to fix Safari to show your icons, I'm sure.

Getting Microsoft Internet Explorer for Mac happy is a different subject. From all I can tell, MSIE only grabs the favicon.ico graphic if you bookmark the site. Otherwise it just uses the generic icon that's used for every other Web site on the net.

Just for good luck, you are using the right format for your favicon too, right? There are two approaches. The basic one is:

<link rel="shortcut icon" 
  href="http://www.askdavetaylor.com/favicon.ico"></link>

but if you don't want to monkey with the ".ico" graphics format, it turns out that other common Web graphics formats are supported, including GIF, JPEG and PNG. To use one of those, specify the "MIME" filetype:

<link rel="shortcut icon" type="image/x-png"
  href="http://www.askdavetaylor.com/favicon.png"></link>

I hope that helps you out and gets everything working as you want!