SilverSpirit - 6:28 am on Mar 8, 2012 (gmt 0)
According to webdesign.about.com
The <fieldset> tag is valid within the following tags:
blockquote, body, center, dd, div, fieldset, form, iframe, li, noframes, noscript, object, td, th
and it seems to work like that in all browsers, including on my Android.
Not sure about the source of that information, though.