Six members of Evan Bayh's group have indicated they are open to a public option: Tom Carper (DE), Kay Hagan (NC), Mary Landrieu (LA), Glanche Lincoln (AR), Claire McCaskill (MO), and Mark Warner, (VA). That makes 49.
Arlen Specter, who falls into a class of Senator all his own, has also indicated he is open to a public option. That makes 50.
Without the 60-vote option available to Republicans on health care, that makes enough to pass a public option in the health care bill. As such, it could really happen. And it needs to happen, as it is the only real way to keep down health care costs and make health care available to everyone.