Our first preview for Mono 2.0 is out; It has been almost six months since we branched version 1.9 so this is a gigantic update to Mono.
Many of the features are listed on the release notes, but the release notes do not even begin to capture the enormous number of fixes, performance improvements, tuning and work that went into this release.
As usual, this is our "best release ever", but it is also the longest we have gone without doing interim releases, so it is possible that we might have regressed where our test suite lacks tests. We would love to get folks to test this, with their code, and to bug reports on any issues they find before our final 2.0 release.
See our Roadmap for more details on the release schedule and the upcoming post-2.0 releases.