Jira  Agile  Scrum Board  Work has columns with these titles:To DoIn ProgressDoneCan the text for these titles be changed?
Jira  Agile  Scrum Board  Workchange text of column titles?
jira
In version 6 of Greenhopper (Agile) and probably earlier versions, you can do this by going to the Scrum Board, then selecting Tools > Configure from the menu on the right. Then select the Columns tab if it isn't already and you should then be able to in-line edit the titles by clicking on them. 