Not that it is any consolation to those anxiously waiting for this release, but isn't it typical for Orbx products to show up on Steam at least a week or more after release on Orbx direct? At least this seems to be the pattern with other products they have released. I would think it will be the same with service packs.
A few threads on this forum and on Orbx forums have led to the recommendation to buy from Orbx direct and not on Steam if you want the most current releases sooner.