www.everydayphoenixwoman.com is the blog and I've changed the blog name/Title to be using a script font under the Ata Theme options...

font-family: Corsiva, "Lucida Handwriting", cursive;

Is this a firefox thing or have I done this wrong? Because it's working in Internet Explorer...

Fonts are a 'interesting' issue and it a browser/machine issue. You can pick a font that looks great, but it the person viewing it dosn't have that font, or the browser soesn't support it.....it won't display. That is why you specify multiple font's and the last shoud be a web safe font.

If you don't specify at least one font that the viewer's browser/machine supports, they won't see anything. Now try to get Apple, Google, Modzilla and Microsoft agree on fonts they will all display the same way...oh could you get me a couple of teh ice cubes from Hell? (grin)

Do a google search on 'web safe fonts'