While there is still no official release date it was announced that a Mac/Linux version will come out shortly after 1.3 is released which is on the 30th.

Source: http://forums.terraria.org/index.php?threads/good-bad-im-the-guy-with-the-yoyo-the-terraria-1-3-official-trailer.20072/

Yay, great! I also hope that they will release a Linux server as it is very difficult to set one up at the moment.

Well the 1.3 update is supposed to be fixing that since setting up a server on windows is also a bitch. 1.3 is going to just use Steamworks for multiplayer, so hopefully the GOG version of 1.3 will use Galaxy.api.

Also just saw from Loki(Re-logic's community manager) that the Mac and Linux version is planned to be released by the end of July.

I hope that they will make a Galaxy-less (and Steam-less, of course) multiplayer (at least for LAN games) as I don't want to try to install Galaxy on Linux.

Well depending on how much they changed in 1.3 it's possible they could keep the old multiplayer system for those who don't want to use Galaxy or Steam.

I certainly hope so. Or that it is otherwise possible to change / mod the game in order to get the old multiplayer back.

Awesome news! I had given up hope

Well after playing the Steam version, they kept the old IP based multiplayer on top of the new steamworks MP, so if/when they add Galaxy support it most likely will be the same. I really didn't after they showed off the screenshots of the Mac and Linux version in action. Which was more then what they had way back in 2011-2012 when Red last tried to do a Mac port. So it seemed to me that they made alot more progress for them to show something off and say "hey we are working on a Mac and Linux version) I just figured it may have taken sometime since they had only three coders by this point(before it was just Red) and they had one leave due to family issues, leaving them with two for a while but now they are back to three and still had 1.3 in development.

But last I heard about it, they plan on hopefully having the Mac and Linux versions ready by the end of the month.