Edit: It appears that we were all fooled by our optimism. No DRM was always the default; this change was more of an 'opt-in to DRM'. See http://www.theregister.co.uk/2010/01...m_drm_changes/
Amazon quietly made a major change to its Digital Text Platform last week that went largely unnoticed: small publishers and individual authors who use the Digital Text Platform can now opt out of the Kindle's digital rights management (DRM) program. While this change only affects a relatively small number of publishers and authors for now, this move could hint at a larger change in Amazon's DRM policy. Right now, Amazon's DRM policy means that its customers can't transfer their books to a non-Kindle e-reader.
Here is the relevant Amazon post: