I've been wondering how important the non-linked part of the DMOZ description is for google results. For example if you have a link that is your company name and the description says 'green widget specialists' -- will google place any value on the description rather than just the anchor text?
Previous evidence suggested that Google does use the Title tag but does not use description or keyword tags for ranking sites (caution: Google's algorithms are not static and what was true a year ago may not still be true or not as true). However, a well-written description tag is still important. If it looks boring, too vague or generic, or too spammy, even placing well in the search results may not be good enough for people to actually click on that link and go to your site/page. It needs to grab the searcher's attention AND be accurate in describing page content. That's why people use the "noodp" tags to prohibit the use of the bland and nondescript DMOZ tags. In addition, Google is not the only player in town, just the biggest, and it would appear that Yahoo and MSN may place greater emphasis on the description tag contents.
The description tag is very important: google shows it in the serps, so that people get to read it (depending on their query). So you should write them with care. Minstrel is right in that it doesn't impact the position in the serps, but since people are going to click (or not) based on what description google shows - and the description-tag is one source for that description - it is important that it describes the page in question (or is left empty). A description that doesn't fit the content is worse then no description.
How google show the description in SERPs depends on the keyword the searcher input. If the keyword meets the content of the page, google will show the meta description tag, or will show the texts with highlighted keyword. Two examples will prove this: 1. Search "website promotion tutorial", the 4th one is my website, and because this keyword related with my content, so google showed the meta description tag. 2. Search "PowerISO Tutorial", the 3rd one is a sub page of my website, because this keyword has nothing to do with the content, visit that page and you will find that the description in SERPs is not from my meta description tag.
The DMOZ-description IS used by google as the text that describes a link, if they think that description is related to what the person is looking for. I don't think it helps in ranking, but it does influence whether a person clicks through or not. If you don't like the DMOZ description, you can ad a no-odp meta tag to your pages that are listed in DMOZ. That way google won't use that description.