http://zuza.appspot.com/4/diff/24/9
File translate/storage/pocommon.py (right):

http://zuza.appspot.com/4/diff/24/9#newcode66
Line 66: name = "Gettext PO file"
Some thought needs to go into what to do with template .pot files.  Perhaps
these need to be a separate class inherited from a generic PO class.

http://zuza.appspot.com/4/diff/24/9#newcode68
Line 68: mimetype = ("application/x-gettext-catalog", )
This is the wrong mimetype I think it is meant to be text/x-gettext-catalog -
check in VirTaal

Just an aesthetic tweak ..

http://zuza.appspot.com/4/diff/24/7
File translate/storage/factory.py (right):

http://zuza.appspot.com/4/diff/24/7#newcode203
Line 203: supported.extend([(name, extension, mimetype)])
Why the one-element list? 
Why not 'supported.append((name, extension, mimetype))'?

Just some readability notes from an outsider.

http://zuza.appspot.com/4/diff/24/8
File translate/storage/mo.py (right):

http://zuza.appspot.com/4/diff/24/8#newcode53
Line 53: print "\\x%02x"*len(s) % tuple(map(ord, s))
This doesn't actually return a Python string. It looks like it may be meant for
debugging use from the commandline (i.e. print something that can be pasted into
Python code), but I don't know from the docstring.

http://zuza.appspot.com/4/diff/24/8#newcode56
Line 56: def my_swap4(result):
Docstring?

http://zuza.appspot.com/4/diff/24/8#newcode64
Line 64: def hashpjw(str_param):
English variable names please?

http://zuza.appspot.com/4/diff/24/8#newcode107
Line 107: def __init__(self, inputfile=None, unitclass=mounit):
Here and elsewhere:
"Method definitions inside a class are separated by a single blank line."
http://www.python.org/dev/peps/pep-0008/

http://zuza.appspot.com/4/diff/24/8#newcode121
Line 121: hash_cursor = V % S;
Would it hurt to expand V and S to words?

http://zuza.appspot.com/4/diff/24/8#newcode150
Line 150: hash_table = array.array("L", [0] * hash_size)
Hash tables are useful for many things. Could the name say what this one's used
for, rather than just saying that it is a hash table?

http://zuza.appspot.com/4/diff/24/8#newcode161
Line 161: string = MESSAGES[id] # id is already encoded for use as a dictionary
key
Masks 'string' module; undescriptive in same sense as 'hash_table'.

http://zuza.appspot.com/4/diff/24/8#newcode225
Line 225: context, source = source.split("\x04")
It looks like you know for certain source will never have more than one "\x04"?