One of the many surprises about the BlackBerry PlayBook is that it shipped with no native email client. In other words, unless you connect it to your BB you don't have a native email client. You can of course do webmail.
Research in Motion says they will release a native email client this summer, and they took some time to demo the new client. The client will support BES and BIS and will give users the full BlackBerry experience. The nice thing is you don't have to rely on bridging the PlayBook to a BB.