Rack Performer version 0.95-alpha is now available here.
With the brand new Master Clock and its associated Transport Bar the fun really starts now, as you are able to play with sequenced instruments and time synchronized effects.
The Transport Bar is packed with useful features to make hand-synchronization with other musicians a breeze, like Sync-to-push, Tempo Tap and Tempo Skew which works like you would do when "pushing" or "slowing" a vinyl.