We are using Ushahidi Platform for bettermap.org.So you can use the Ushahidi v2.X REST-API.
To get the data out of bettermap.org take a look at the Ushahidi Public API.
In Ushahidi the entries on the map are called 'incidents', so you can retrieve all bettermap entries by using:
To get a certain entry you can filter this way:
Or you can retrieve just all entries belonging to a certain category this way:
The output is JSON by default. If you wish XML you can add &resp=xml to the API call.
But that's all documented by the links above ;-)
Have fun, and please let us know what exciting stuff you did with the bettermap data.