Another workaround, instead of using Java WebStart, is to use the "open" command with the -n flag.  Bring up the Terminal program (via the Finder; go to Application::Utilities).  Select Shell->New Window->Basic, and a terminal window will pop up. Assuming the BioTapestry Editor icon is on your desktop, type:
cd Desktop
into the terminal.  Then type:
open -n 'BioTapestry Editor.app'
hit return, and wait.  Do this as many times as you want.  Each time will bring up a separate instance of the BioTapestry Editor program.
Sorry for the hackish workaround.  We're still looking into the long-term alternatives.
Bill