Short, but very obfuscated (don't do this):
print 'ny'[len(s) > 5]
[edit] the reason you should never do this, is because it uses properties of the language that are little known to most people, i.e. that bool is a subclass of int. In most situations where you find yourself writing code like the OP, it's usually better to create a flag variable
s_is_long = len(s) > 5
then you can use any of the more appropriate ways to write the print, e.g.:
print 'y' if s_is_long else 'n'
or
print {True: 'y', False: 'n'}[s_is_long]
or the most readable of all...
if s_is_long:
print 'y'
else:
print 'n'