Just a quick note, TinyMCE 3.4.6 is now out.
Several IE fixes again:
Fixed accessibility bugs in WebKit and IE8 where toolbar items were not being read.
Fixed bug where anchors wasn't updated properly if you edited them using IE 8.
Fixed bug where the media plugin wouldn't work on IE9 when not using the inlinepopups plugin.
Fixed bug where the style attribute of layers wasn't properly updated on IE and Gecko.
Fixed bug where IE 6/7 would produce JS errors when serializing contents containing layers.