If I use the encodingName method via Obj-C it returns nil if the encodingName hasn't been expressly set on the WebView. It would be nice if it returned the encoding that WebKit used to render the page instead of nil.
<rdar://problem/5316261>
See also: <rdar://problem/3529874>.
FWIW, the input encoding is available from HTML (and XML) DOM as document.inputEncoding.