I don't think you have anything to worry about with regard to intent,
but there are a couple of things that you might want to consider...

You might avoid a "grain of sand" if you don't give the spans in your
menu a class of "hidden", that's got to ring some alarm bells
somewhere. You don't need a class there at all, just apply your css to

#primary_navigation span, #navigation_search span { ...rules in
here... }

You should also be aware that using display:none for this text can
cause problems for screen reader users. Not only do regular browsers
not show the text (which is what you want), many screen readers don't
read it out either (which isn't). If you only want to hide text
visually, but still get it read out, use absolute positioning to
"display" the text somewhere off the screen, say at top:-9999px .
http://www.google.com/search?q=screen+reader+display+none will find
plenty of stuff on this issue.