Seems like Opera Software has adopted one of the customs that is quite common in the FOSS scene: Weekly builds :D
The goal is to further open up our development process to our devoted users and allow you to be more involved at an earlier stage than when we ship the next public beta. Johan Borg
… and the first build for Windows and MacOSX already comes with fixes to some bugs I’ve noticed while playing around with the 2nd technical preview like for example the not really working BitTorrent support on Mac. The whole process still seems to suffer from some teething troubles that seem to be the cause for the missing Linux build.