You can check by looking at the source code of a given page. If your links have the attribute rel="nofollow" then they are nofollow links. Otherwise, they are considered follow links.
Another option is to install a browser plugin or addon which highlights nofollow links. One example for firefox is Quirk SearchStatus, but there are others as well.
Read more information about this topic and how Google handles "nofollow" here:
http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=96569