I installed the geo location pluggin and then restarted my N900. I still got the same error message you received. Google maps can get my lat long coordinates, but facebook places can't so I don't know if it is an issue with facebook or my configuration on the N900.

Nobody has indicated they have actually checked in. The other posts indicate that they can select a location from a list, which I can do also, it is the actual check in where I get the error and I am guessing you are getting the error also. It would be helpful to know if anyone has made it all the way though the check in process so that their location appears on their wall is we know that it is possible with FB.