The attached patch allows for shell curly braces with fnmatch.filter().

This makes the following possible:
>>> import fnmatch
>>> import os
>>>
>>> for file in os.listdir('.'):
...     if fnmatch.fnmatch(file, '*.{txt,csv}'):
...         print file
...
file.csv
file.txt
foo.txt

This is especially convenient with the glob module:
>>> import glob
>>> glob.glob('*.{txt,csv}')
['file.csv', 'file.txt', 'foo.txt']

Hopefully, this makes fnmatch match better the behavior that people expect from a shell-style pattern matcher.

Please note: I attached a patch that applies on the Python trunk, but only tested it on Python 2.5 on Windows. However, the fnmatch module doesn't seem to have changed substantially in between.