Ampersands in #+AUTHOR: declarations are not correctly escaped by Org-mode.
To reproduce, export: #+AUTHOR: a & b You'll find the line <meta name="author" content="a & b"/> in the output, but it should be <meta name="author" content="a & b"/> The same problem occurs with other special characters in author declarations, and also in #+DATE: declarations. This is breaking the "XHTML 1.0 Strict" claim. - Pavel Panchekha