Request underscores (or some other standard delimiter) be officially supported in project keys. This is to address the documentation note "If you use GreenHopper or have integrated JIRA with Bamboo, you should avoid changing JIRA's default project key format as both GreenHopper and Bamboo only support this key format." Underscores in project keys seemed to work find in JIRA 4.4, but there is a known bug in 5.1 related to the activity stream (JRA-27967). That bug is not within the scope of this issue; this issue is to ensure future JIRA upgrades will not cause additional problems with GreenHopper, etc, for projects having undersores in their keys.