Airplay on Bluetooth speaker paired to Mac I've got a Bluetooth speaker (a JawBone Mini) and I paired it to my Mac.
I can set it as output device from System Preferences -> Sound -> Output but I would like to use it as an AirPlay speaker, as I do on my iPhone. Is there a way to do that?

(In iOS, this speaker works great with AirPlay)
Unfortunately, this is not possible.  The reason you can Airplay with your phone and not your Mac, is due to the fact that the Jawbone Mini app appears to convert the Bluetooth speaker to an Airplay device as shown here. 

https://jawbone.com/kb/articles/JawboneappiOS.html and here http://appadvice.com/appnn/2013/12/review-jawbones-big-jambox-could-be-the-best-portable-speaker-out-there (the second link is for the Jawbone Big Jambox, but the app is the same). 

However, you should be able to pair the speaker with Bluetooth and still use it. If you want it to show up in the Airplay speaker menu, you need to build a DIY solution with a Raspberry Pi or purchase an Airplay Compatible Speaker as zero said above. 

Hope this helps.