From what I've read Java 6 is still there somewhere and that's how we can get the Launcher to start with the terminal commands. I still don't know why there is a mismatch in the download process. This comes up in the log 'Downloaded 'minecraft.jar' does not matche MD5 of any known minecraft version!'. I think it may be that the Launcher is recognizing the 1.4.2 update as a valid minecraft build. I don't exactly know however. I don't know what the MD5 part means.
On a side note, you and I are the only two I have found so far with this problem running on Mac 10.7.5.