Atlassian Connector (3.0.4, SVN:1203151109) for Intellij (11.1) stopped working when updating Jira to v5.0.1#721-sha1:838c4a0.
The root cause seems to be java.lang.IncompatibleClassChangeError: Found interface com.atlassian.jira.plugin.searchrequestview.SearchRequestViewModuleDescriptor, but class was expected