This code should do the job. One of the answers to the question Parse annotations from a pdf was very helpful in getting me to write the code below. It uses the poppler library to parse the annotations. This is a link to annotations.pdf.
code
import poppler, os.path
path = 'file://%s' % os.path.realpath('annotations.pdf')
doc = poppler.document_new_from_file(path, None)
pages = [doc.get_page(i) for i in range(doc.get_n_pages())]
for page_no, page in enumerate(pages):
items = [i.annot.get_contents() for i in page.get_annot_mapping()]
items = [i for i in items if i]
print "page: %s comments: %s " % (page_no + 1, items)
output
page: 1 comments: ['This is an annotation']
page: 2 comments: [' Please note ', ' Please note ', 'This is a comment in the text']
installation
On Ubuntu the installation as as follows.
apt-get install python-poppler
