@speedyk - my initial thoughts on doing migrations are based on file & SQL (similar to, but not identical to, some of the existing plugin solutions out there).

Attachments are a huge, huge part of what can be improved -- but so too are settings, users, plugins & themes. It occurred to me when planning the project that these are areas where native file archives (.tar.gz, for example) and SQL dumps have served developers well for years. The challenge is figuring out how to avoid downloading and reuploading 1.5 GB media libraries, for one, and how to make it easier to clone an installation without having to set up a new WordPress installation first to be able to import.

However, the exporter/importer remains an important part of WordPress, and I'm looking at what I can do to make it better. It's a really tough problem on the development side!