Microsoft has begun rolling out Skype version 8.66 to all users that brings support for up to 100 call participants on all supported platforms. There is the usual suite of bug fixes as well.
Skype 8.66 RSS
Microsoft has released a new preview version of Skype, bringing it to version 8.66. With the latest update, it's now possible to have calls with up to 100 participants, double the previous limit.