Using the new search features, you can easily request "all colleges within 5km of San Francisco" and apply attribute filters like "[Type:public]". You can also sort the results by proximity to a point (in this case, the center of the map). The results are updated whenever the map is dragged or zoomed, or when the search criteria change.
In addition to search, many developers have requested the ability to enable API access to a public map without requiring users to be signed into a Google account. We've also enabled this today: you can indicate (using the API) that you would like a map to be accessible by others via the API. You can also programmatically control access to the maps you own, by making them public/private or adding specific collaborators. Our official docs will be updated soon but, in the meantime, check our forum for updates about this.
To get started writing your next awesome geo app, you can download and modify our sample code, or refer to our documentation. We look forward to seeing all the great collaborative mashups, store locators, and mobile apps you'll come up with.
If you have questions or feedback, or would like to tell us about your new creation, please visit our developer forum, tweet about #mapsdata, or file a feature request. We have some other great features on the way, so stay tuned and keep mapping!