Creating a model named Format result in code 406

I have created a vanilla Rails3 app and scaffolded a model named Format with one attribute 'name'.
If I send any Post-request to the controller (create or update), it actually performs the Action in the database (i.e. creating or updating the record), but it returns a code 406 to the browser:

Started POST "/formats" for 127.0.0.1 at Mon Jul 12 11:11:03 +0200 2010
  Processing by FormatsController#create as 
  Parameters: {"commit"=>"Create Format", "authenticity_token"=>"ZX5QeLvPrLuypcp0byaBtNGfRQUGX0zuP7/lgP7GwZI="}
  SQL (0.5ms)  INSERT INTO "formats" ("created_at", "name", "updated_at") VALUES ('2010-07-12 09:11:03.710452', 'Test', '2010-07-12 09:11:03.710452')
Completed 406 Not Acceptable in 24ms

I guess this happens because Rails because Rails uses 'format' itself internally and mixes something up. This should either work, or Format should be a reserved word that should not be allowed as a model/controller name.

Version:

ruby 1.8.7 (2010-06-23 patchlevel 299) [i686-darwin10.4.0]
Rails 3.0.0.beta4