Trolltech has to released Qtopia Greenphone SDK Light v4.2.1 to its customers today. Qtopia 4.2.1 includes the following:

  New features in Qtopia e.g. in the areas of Bluetooth, and API support for DRM
  New features that utilize capabilities from Qt 4.2, e.g. SVG support
  Improved performance

Qtopia Phone SDK, though not necessarily relevant to Greenphone, also includes:
  Support for Multiple Screens
  Sample VoIP implementation

You will find more information on the Qtopia platform and the GreenPhone on Trolltech website.