Google has released a new snippet format that extracts details from long lists and displays them in a bullet-point. The snippet format replaces meta descriptions and is used for sites that give categorical listings.
The new snippets were first spotted about a week ago, and at that time was primarily being seen in the UK. However, a recent Inside Search post confirmed that the list snippets were a search engine results page addition that all users should see by the end of the month, give or take. Here's how the new snippets work.
Pages that display long lists of category-specific details, typically relevant to a specific location, may have segments of that list used in a compressed bullet-point for their snippet. Three items are displayed, but Google also notifies users of approximately how many items are present in the list total (5+, 10+, 30+ items, etc.). The first line of the standard snippet (typically the meta description) is also shown.
Here's an example search for "electricians Salt Lake City, Utah":
Since you're getting three bullet items in addition to your standard first line, the format increases page real estate and could also increase click-through. The addition seems to work pretty well for pages that have long lists; some users may even be able to stop at the SERP, while others will know the general list structure of the page they're going to.
This isn't likely to be the last snippet change, either. While Google takes its time experimenting with new designs, the Inside Search post announcing the change specified that, "We’ll keep making more snippet improvements to better reflect the content of our search results, making it easier for you to find the most relevant results."