I know in a lot of source control tracking systems (Redmine, Trac, Jira) you can add magic words like
resolves #1234 in your commit message to have the bug updated to a certain status. Is there a feature like this with Launchpad - if so where, or what, is the list of magic keywords?
An example can be seen on Redmine's issue tracker page.
http://www.redmine.org/issues/6987 has two "Associated Revisions"
They're associated because the commit message has Fixed: Wiki#find_page should not be case sensitive because page title uniqueness is not (#6987). The combination of Fixed as a keyword and #6987, bug's unique ID, automatically updated the associated ticked to fixed.