Breast reduction has evolved from an inpatient procedure with a 1-3 night hospital stay as recenly as 10 years ago to a routinely outpatient procedure.  The factors involved are:

• better anesthesia (more propofol, less inhalational anesthesia) which helps speed recovery and reduce nausea
• The routine use of local anesthesia with epinepherine injection at the initiation of the procedure decreases blood loss significantly.  For example, when I was in training it was fairly routine to have a patient donate blood a few weeks before the procedure in preparation for a possible transfusion.  Now my blood loss is literally a teaspoon or two.
• The above allows many plastic surgeons (such as myself) to do the procedure without hardly touching the cautery device.  Less burn = less swelling and pain.
• Quicker procedures = less anesthesia
• Routine use of premedication for nausea

For patients whom are paying out of pocket,  I do this procedure in my clinic operating room (unless there are contraindications) with deep sedation with an anesthesiologist and excellent local anesthesia.  These patients often feel ready  to go home 15 minutes after the procedure, although I keep them longer for monitoring.