YES. The CBL 2 and LabPro interfaces do support digital output and can be used with the Digital Control Unit (DCU-BTD). You can find sample programs for the DCU at
http://www.vernier.com/downloads/software-development-kits/dcuprogs/

In addition to digital output, LabPro has analog output, which is used by connecting the standard voltage probe to CH4. Details of how to use the analog output lines are in the LabPro Technical Reference Manual or from How do I use the function generator and analog output feature of LabPro?.