Kewl news, yesterday Microsoft released the Skype for Business Technical Preview client. I have started playing with it in my lab and on my production machine and have been really finding the experience pretty good.
If you would like to give it a whirl you can download from here http://www.microsoft.com/en-us/evalcenter/evaluate-skype-for-business.
One of my colleagues first question was "does it have a mute/unmute hot key?" and low and behold it does. So have a squiz at it, the experience on the whole for me over the first 24 hours is, it is great :). I am excited!