Sony announced at NAB that they would be adding Blu-ray support to DVD Architect with version 5.  Well the new version is here . We have not actually had a chance to have a proper play ourselves, although we have been using the  non-Blu-ray 4.5 for authoring DVDs for some time and like its huge amount of features and configurability. 
Here is what's new in version 5.0

    * Burning to Blu-ray Disc
    * Full-screen previewing to secondary Windows display
    * Support for opening MPEG-2 and AVCHD video files
    * Support for using AC3 and PCM audio with HD video
    * Support for creating .iso files and burning to DVD or Blu-ray Disc

The best thing is that its free to anyone who owns Vegas 8.  Just download the new version and install.
This now means we have 3 decent programs for making Blu-ray discs - Adobe Encore, Sonic DVDit Pro HD (also known as Avid DVD) and DVD Architect.  We will be compiling a proper list of whats good and bad in each soon.
You can download the new patch here.
Or you can order Vegas with DVD Architect 5 from the DVC Webshop.