If the data is still in mysql, I'd have mysql do the work, and use the DATE_FORMAT() function.

In more recent versions of mySQL, there's also the CONVERT_TZ() function (but you'll need to load the time zone tables)

The following should work in most versions of mysql:

date_format
  date_add('20050519112656',interval 4 hour),
  '%m-%d-%y %h:%i %p EST')
[download]

(I'd also personally suggest not using m/d/y ordering ... it might make sense to americans, but can cause lots of problems down the road... y/m/d tends to be more universal, as there's no ambiguity)