I've been working on getting Rasterio to 1.0 this spring. Today I tagged the project 1.0b1 and uploaded a source distribution and wheels for macosx and manylinux1 to PyPI: https://pypi.org/project/rasterio/1.0b1/.
There are many changes in this release. We've fixed a number of bugs and added new features. We've deprecated some features and removed features that were previously deprecated. The full list of changes is at https://github.com/mapbox/rasterio/blob/master/CHANGES.txt#L4-L108.
Please try this pre-release out soon and check for warnings and hopefully rare and minor un-warned bad surprises.
I've had a lot of help getting to this first beta release and had a lot of fun tweeting thanks this afternoon. Brendan Ward isn't on Twitter as far as I know and so I want to acknowledge his contributions here: thanks!