Forum Moderators: open
Rarely. They almost always display a "snippet" - words and phrases from your page which best match the entered search terms.
The only way to get them to display your description is to take all other text off the page. That wouldn't be very wise. Most of us just live with it, although you CAN improve the snippet for your most-often-used search terms by careful grouping of keywords into your on-page copy. It's best not to go too far with this to the point that the text on the page no longer reads well.
If you are listed in the Open Directory Project directory, Google will also include the description from your ODP listing.
HTH,
Jim