Show/hide description
It looks pretty clean. You are saving the values into variables so to avoid re-running the query.

A minor improvement would be to use click function instead of on('click') as it more readable.

For the toggle part, one can identify 2 phases when clicking:


change button text
animate the description


If you don't need to keep them separate you can remove the ternary operator (the expr1? expr2: expr3) and do:

showHide.click( function () {
    if (longDescription.is(':visible')) {
        showHide.text('Read More');
        shortDescription.fadeIn(inSpeed);
        longDescription.fadeOut(outSpeed);
    } else {
        showHide.text('Read Less');
        shortDescription.fadeOut(outSpeed);
        longDescription.fadeIn(inSpeed);
    }
});