Check locally installed packages against one or more package indexes for updates and list them. Using subprocess instead of stdout (wasn't working on my MacPython 2.6.1). Removed curses dependency to allow it to work on windows.

check_for_updates.py

#!/usr/bin/env python
"""
Use pip to get a list of local packages to check against one or more package
indexes for updated versions.
"""
import sys
import xmlrpclib
import subprocess
from distutils.version import StrictVersion, LooseVersion


def get_local_packages():
    """
    Call pip's freeze -l
    
    returns a list of package_name, version tuples
    """
    cmd = ' '.join(['pip', 'freeze', '-l'])
    process = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True)
    out, err = process.communicate()

    pkgs = out.split('\n')
    return [p.split('==') for p in pkgs]

def find_current_version(package, index_urls=None):
    """
    Using the XMLRPC method available for PyPI, get the most recent version
    of <package> from each of the index_urls and figure out which one (if any)
    is higher
    
    Returns a tuple of the index with the higher version and the version it has
    """
    if index_urls is None:
        index_urls = ['http://pypi.python.org/pypi',]
    cur_version = '0'
    cur_index = ''
    for index_url in index_urls:
        pypi = xmlrpclib.ServerProxy(index_url, xmlrpclib.Transport())
        pypi_hits = pypi.package_releases(package)
        if len(pypi_hits) > 0:
            if compare_versions(pypi_hits[0], cur_version) == 1:
                cur_version = pypi_hits[0]
                cur_index = index_url
    
    return cur_index, cur_version

def compare_versions(version1, version2):
    """
    Compare 2 versions, starting with StrictVersion, and falling back on
    LooseVersion
    """
    try:
        return cmp(StrictVersion(version1), StrictVersion(version2))
    # in case of abnormal version number, fall back to LooseVersion
    except ValueError:
        return cmp(LooseVersion(version1), LooseVersion(version2))

def output_line(pkg_name, new_version, old_version, index_url):
    """
    Output the line showing the formatted information
    """
    print '{pkg_name} ({new_version}) via {index}. Currently {old_version}'.format(
        pkg_name=pkg_name,
        new_version=new_version,
        index=index_url,
        old_version=old_version.strip(),
    )

NEWER = lambda x,y: compare_versions(str(x), y) == 1

if __name__ == '__main__':
    if len(sys.argv) > 1:
        indexes = sys.argv[1:]
    else:
        indexes = ['http://pypi.python.org/pypi',]
    print "Packages with newer versions:"
    print ""

    for pkg in get_local_packages():
        # pip outputs a single 0 at the end of the list. Ignore it.
        if len(pkg) < 2:
            continue

        index, current_version = find_current_version(pkg[0], index_urls=indexes)
        if current_version and NEWER(str(current_version), pkg[1]):
            output_line(pkg[0], current_version, pkg[1], index)