This December saw a WIP release of Allegro 5. There are still several milestones to be hit before a full release, but the API is now stable enough for Allegro# to target.
Will work continue on Allegro# 0.8?
Tweaks, yes. Real development, no.
Will Allegro# ever see a 1.0?
If it does, it won't be from my hands.
The two features keeping it from 1.0 are 3D and GUI, both of which are sorely outdated and hackish. To translate them to C# would likely be clunky, and not very useful for most developers. If someone else wants to work on them, that would be awesome, but I've decided to spend my time elsewhere.
When will Allegro# 2.0 be released?
Whenever Allegro 5 is. I'll probably keep pace with their WIP releases, but ultimately I can't make a definitive release until they do.