According to a post on the Unified Communications Group Team Blog we can expect a public beta of the Release Candidate in a few days.
From the blog:
“Thousands of people in our early Technology Adopter Program, or TAP, already rely on “14” to provide their phone, conferencing, messaging, and other communications, many of them since February. This number will increase dramatically when we make the release candidate (RC) software available in a few days.”