I think I have an explanation:
All audio as of Logic 9 has embedded tempo information now. And don't all apple loops have embedded tempo information anyway (even before L9)? But they don't all display that metronome glyph. So, I'm wondering what the specific factor is that causes that glyph to be displayed.
I tried importing Logic's apple loops both through the loop browser and manually through the add audio file function. Neither yielded the metronome glyph.
Then I tried importing another aiff apple loop from another library and lo and behold; I got the metronome icon!
So, maybe it has to do with file format. CAF apple loops don't display it, but aiff apple loops do? Thats' the closest I can come to a logical explanation!
So, my conclusion is this:
* Files with embedded tempo information don't necessarily display the metronome glyph.
* Files with embedded tempo information that are in a compressed format, like CAF, don't display the metronome glyph.
* Files with embedded tempo information that are in a full fidelity format, like aiff, do display the metronome glyph when imported with their tempo information.
Try importing an apple loop that's in aiff format. You should get the metronome glyph.....
Here's a screen shot from my experiment.