Here's just one study based on real wounds:

Prospective evaluation of topical antibiotics for preventing infections in uncomplicated soft-tissue wounds repaired in the ED.
Acad Emerg Med. 1995 Jan;2(1):4-10.

This comparison study showed that use of a number of different antibacterial ointments resulted in fewer infections later on compared to those using petroleum jelly as a control (to rule out the effect of the "keeping the wound moist and protected" idea). Triple antibiotic ointment (like Neosporin) was among the best of the antibacterial compounds tested.

This study:

Contemporary antimicrobial activity of triple antibiotic ointment: a multiphased study of recent clinical isolates in the United States and Australia.
Diagn Microbiol Infect Dis. 2006 Jan;54(1):63-71.

...made me feel better about triple antibiotic ointment. It showed that Neosporin worked against even MRSA, even those samples that were resistant to Mupirocin, even though these antibiotic compounds have been in widespread use for decades.

Anyway, FWIW.