In a potentially huge blow to local services like Yelp, CitySearch, and AOLCityGuide, Google is now offering users the ability to leave reviews for businesses they search on.

To date, Google has aggregated reviews from those sites and others in its local search results. Now it’s soliciting reviews directly. It lacks the community features of Yelp, but the tight integration into Google Maps will likely serve the needs of casual users.

One of the challenges with reviews is getting people to write reviews — sometimes, they just need a nudge. Google could use your search history to remind you. Did you get driving directions to a restaurant last week? A subtle reminder could appear when you return to Maps, encouraging you to write a review. (Kind of like the Netflix emails when you return a movie.)

More on: Google, maps.