XML comment syntax for XHP is one of the top wishlist items within the UIE group (+ some other people).
Currently, the only way to have comments inside XHP blocks is to use expressions and block comments, e.g.
<div>{/* comment */}</div>
After this change, you can use the more familiar syntax. This syntax is limited to XHP child contexts:
// Only single-line, doc, block comments work outside XHP
$xhp =
<div>
<!--XML comments only work within XHP children contexts-->
</div>;
Based on http://www.w3.org/TR/REC-xml/#sec-comments - except we ignore the rule about double hyphens ('--') within a comment because we don't care about SGML.
Kyle Delong