Oops...we don't have a job for you after all, sorry!

I want to share my recent experience of being offered a job and then having the offer withdrawn...all within in 72 hours! I am a new grad and was offered a part-time position at a LTC facility. We discussed the salary, an offer was made, and I was scheduled to attend an eight-hour computer training class later that week, from 8:00 am-5:00 pm (job offered on Monday, training scheduled for Thursday of the same week). Wednesday afternoon, the day before the computer training, I received a telephone call from the ADON who had hired me. I missed her call, but returned her call within 30 minutes. That is when she informed me that "she didn't have a spot for me." I initially thought she meant that she was unable to squeeze me into the computer class, given the fact that I was hired and scheduled for the computer training the same day. Her tone and conversation were peculiar, as if there was something she needed say, but was afraid to speak. After a bit of prodding, I asked her if she was actually calling not to cancel my computer training, but to withdraw the job offer. To my total amazement, she said, "YES"! The excuse she gave was because the "job had already been filled and she did not know that." My mouth dropped. Did I mention that I had met both the ADON and the DON? Neither knew the job had been filled??? How can that be??!! Am I missing something?? I find this practice highly unprofessional and unlike anything I have ever experienced!! She promised to give me the next job that becomes available. NO THANKS! As of today they are actively still recruiting for RNs at this facility. I saw their job posting and laughed out loud!! While I wanted the job and believe I would have been a great addition to the staff, I am counting my blessings. I think working for that organization and that management team in particular would have been like having my worst nightmare come alive. I am posting for two reasons: 1) While I don't want to suggest that withdrawing offers is commonplace, I want to let other hiring managers know that this practice is crushing to eager new-grad applicants, and 2) to find out what others think of this practice? Maybe I am overreacting but, at best, I think this sucked. I will reserve more colorful language for another time and place but, believe me, I could say more--lots more. Your thoughts?