You can use the xapian DB directly:

import xapian

db=xapian.Database("/var/cache/software-center/xapian")

for m in db.postlist(""): 

    appname = db.get_document(m.docid).get_data()

Or the internal software-center API:

import sys

sys.path.insert(0, "/usr/share/software-center/")

import softwarecenter.db.database

db = softwarecenter.db.database.StoreDatabase()

db._aptcache.open()

# 'use_axi' is use apt-xapian-index

# 'use_agent' is use the Software Center Agent database

db.open(use_axi=False, use_agent=False)

for doc in db:

    app = db.get_application(doc)

    print app.appname, app.pkgname

    appdetails = app.get_details(db)

    # Icon names are relative to /usr/share/app-install/icons/

    print appdetails.icon