Ok, I have uploaded an SVN snapshot of the next version of AgateLib here. The API is at the point where it is mostly stable, but there is still bug testing that needs to be done and there may still be some API changes. These things will go faster and be more complete if others can help out with the testing.
Edit: 0.3.0 has been released, so the preview download has been removed.
There are several breaking changes in the API if you want to migrate from 0.2.5. I'd recommend backing up your project before updating to 0.3.0. Below is a list of particular issues and fixes.
Namespaces no longer start with ERY.AgateLib, instead they are all in the AgateLib namespace
Classes related to drawing are moved to AgateLib.DisplayLib namespace.
Classes related to audio are moved to AgateLib.AudioLib namespace.
Classes related to input are moved to AgateLib.InputLib namespace.
Input class for interface is deprecated.
The Sprite class has been replaced by a new version.
This has not been thoroughly tested on Linux or Mac OS, so there may be problems with e.g. audio and joysticks working on those platforms. The display should work fine though.