Working on bug 287345, I noticed that we are losing args passed when the app is starting up. This affects things like |open -a Thunderbird.app foo.txt| but also seems to kill Spotlight results from being loaded. It's possible this is the result of refactoring this code from c++ to js and missing something, but I haven't confirmed that this is the case, so don't want to assume it yet.

open -a Thunderbird.app foo.txt works for me on mountain lion

I've confirmed that David's example is still broken - clicking on a Spotlight result, when Thunderbird is *not* already running, starts up TB with the default UI rather than bringing up the specific requested message.