FWIW, the reason I asked whether a new installation of WebRep is handled properly (whether it is, as one would expect from the Firefox 8 release notes, disabled by default until approved through Firefox) is because some software developers are not happy about features which impede the silent install of addons. I've even seen some discuss possible ways to bypass this Firefox 8 feature. If the software developer is developing software that will only be installed on their own machines (corporate environment for example) that is one thing. However, some of the folks discussing bypass options were developing third-party applications. That, combined with the theoretical possibility of some limitation or bug in the Firefox 8 implementation, makes me think it would be wise to double check the behavior when third-party software installs an addon.