User blog comment:Rappy 4187/Technical Update: October 30, 2012/@comment-4338424-20121031234648/@comment-452-20121101000323

As you saw after submitting your post, the things you typed didn't appear. An admin has edited your post with a &amp;amp; in place of a & so that your post appears as you intended it.

&amp;apos; is the HTML entity for ' (an apostrophe, or single quote)

&amp;nbsp; means NonBreakingSPace and is a special space character which will not cause a linebreak.

For example, this previous sentence with nonbreaking spaces would be: &amp;nbsp; means NonBreakingSPace and is a special space character which will not cause a linebreak (As you can see, because there were no line breaks, the sentence has continued outside of this comment box)

There has obviously been a change in the RTE which encodes special characters as html entities - which is a great idea, I've recently been converting all non-latin characters to HTML entities myself - but apparently the code is also converting apostrophes and spaces in certain cases.

edit: Hilariously, editing comments containing HTML entities here causes those entities to be translated into characters, breaking the examples.

More information:
 * http://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references
 * http://www.w3schools.com/html/html_entities.asp
 * http://www.w3schools.com/tags/ref_symbols.asp
 * http://www.w3schools.com/tags/ref_ascii.asp