The old days of taping signs to a telephone pole are numbered. A new location-based tool called Pinwheel lets people find and leave notes around the world.

Based in Hayes Valley, San Francisco, Pinwheel is the creation of Flickr and Hunch cofounder Caterina Fake. The app lets users mark a pin anywhere they like on the map and leave notes that can either be shared publicly or with certain people or groups; and organized into sets.

The founder had some great suggestions for how to use it, like creating a map of “Every place that you told me that you loved me, circa 2008″ for a special someone. Another genius idea was to post a note requesting someone – anyone – to point out the nearest bathroom. (This could also work for lost pets.) The example below shows a note about the pretty mosaic tile at Grand Central Station in New York City.

 

Said Fake in a blogpost, “Following sets is useful, because that friend of yours with the great taste in coffee shops may also have an unhealthy obsession with, say, 1970s glam metal band KISS, and frankly, in childhood you were traumatized by a photograph of Gene Simmons and don’t need to repeat that in your dotage.”

Pinwheel is a competitor for Repudo, a mobile application for dropping off multimedia like text messages, photos, videos or an audio messages at certain locations for other people to pick up when they get there. Pinwheel doesn’t appear to require users to be physically present to see the notes, which is kind of the point of leaving them online to begin with.

As for its business model, the founder said Pinweel will allow sponsored notes, and she already has some takers. Alex Clark, a realtor with Zephyr Real Estate, will be leaving sponsored notes about properties for sale in San Fransisco.  Author Dinah Sanders will leave sponsored notes about places to recycle to promote her book Discardia.

The company launched last night in private Beta with funding from Redpoint, True, Betaworks, Founder Collective, SV Angel, Obvious Corp, and individual angels. You can sign up to test out the web and mobile web versions here.  A version of the app for Apple devices is coming soon.