Unstable builds, none of them was promoted as "Recommended". Some developers are porting their mods to these 1.8 builds but they're also having issues.
Lol, no 1.8 version for at least half a year! That would need wipe for me though (and for everyone) so don´t rush for that
1.7.10 is good enough for some time
From what I have heard, Minecraft 1.8 made some huge changes to the way textures and other graphics are handled. Some mod authors had a lot of issues with this (I heard that the creators of BuildCraft complained that a fully upgraded Buildcraft would be several petabytes of data. This thread [minecraftforum.net/forums/mapping-and-modding/minecraft-mods/modification-development/2272349-lessons-from-my-first-mc-1-8-mod] on MineCraft Forums talks about it a bit). I think Forge is trying to work around that in order to make things better and easier for mod creators. Looking at the Minecraft Wiki's description of 1.9 [minecraft.gamepedia.com/1.9], I think Mojang is going to try to change things a bit again in order to make things easier for modders.
Forge is officially out for 1.8 as of February 3 (at least I'm pretty sure that is the first non-beta release).
Honestly, I have no plans to update to 1.8, I don't like the way how the game runs, the render lag, mobs are so slow it seems they're in low gravity.
I'm archiving my old worlds (created in beta 1.7.3) and starting a new single-player world from scratch. It will be modded and 1.7.10. Finally I'll play my favorite mods on SP, for real, not for testing purposes. :3