The selected way to distribute the ATF binaries is a zipped update site. The rationale is that there are third party dependencies (like Mozilla XPCOM and some Ajax Toolkits libraries which have not been approved for re-distribution by Eclipse). Using an update site allows to provide update site pointers to install the missing pieces from remote sites like Mozilla.org in one pass.
The build will be using PDE Build.
Mozilla browser fragments specifics
Work in progress
You can check the work in progress on the build there: