I’ve discovered another bug since upgrading to Lion, again in Mail.app.
Try this, it’s fun:
Start writing a new email message. Highlight some text and click the colour palette – we are going to change it’s colour. Make it Red.
So far so good.
Highlight the text again and again click the colour palette, this time change it back to Black by choosing the black square in the top right of the palette.
It turns White.
And there is no way to make it black again. Bug filed with Apple.