One can also go to Mumbai CST or the Dadar railway station and take a train to Pune. Tickets may be booked in advance. For this please see the Indian Railways site.
One can go to Dadar or Borivali (in Mumbai) and take Volvo buses (costs Rs. 450 depending on which day of week you are travelling and from where in Mumbai).
Bus bookings can be made through : Bustrawler.com