import os, sys
from ID3 import *

files = os.listdir(os.getcwd())

for f in files:
	x = os.path.splitext(f)
	if x[1] == '.mp3':
		n = x[0].split(' - ')
		author = n[0]
		title = n[1]
		id3info = ID3(f)
		id3info['ARTIST'] = author
		id3info['TITLE'] = title
		print f+' id3 tagged.'
print 'Done!'

Require the ID3 lib.
Place the script in the directory containing the mp3 files.

Simple ID3 tagger

python

Python