Parsing a subversion Id keyword is just a matter of some regular expression magic:
# use the built in regular expression library
import re
# the subversion Id keyword
svnid = '$Id: svnidparse.py 1234 2008-02-19 09:59:27Z joske $'
# bow for the mighty regular expression
svnidrep = r'^\$Id: (?P<filename>.+) (?P<revision>\d+) (?P<date>\d{4}-\d{2}-\d{1,2}) (?P<time>\d{2}:\d{2}:\d{2})Z (?P<user>\w+) \$$'
# parse the svn Id
mo = re.match(svnidrep, svnid)
# use it, like for example:
print 'this is %s - revision %s (%s)' % mo.group('filename', 'revision', 'date')
hmm, calling it "black magic" would be better, probably.