According to Google's blog (if you haven't noticed) they are now showing longer snippets with search results, for longer queries. So, if a user's search term is longer than a few words, each result will show a longer description.
This is significant, as recent data shows that users are searching longer terms more than ever before - 10% more than last year.
Read about SEO for long queries.
It's now increasingly important that your snippets are descriptive enough to induce clicks from Web users. This means optimizing your meta tags for your pages and/or products and regularly checking search results to see how your descriptions are rendered in results. Your content management system (CMS) might also be helpful in writing strong descriptions.