Doing 

  SELECT (t.*, CONCAT_WS(' ',contact_first_name,contact_last_name) AS creator) FROM ...

fixed the problem.


Original dotProject query:
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mysql> SELECT t.*, CONCAT_WS(' ',contact_first_name,contact_last_name) AS creator FROM task_log t, tasks LEFT JOIN users AS u ON user_id = task_log_creator LEFT JOIN contacts ON user_contact = contact_id LEFT JOIN projects ON project_id = task_project WHERE task_log_task = task_id AND task_project = 1 AND task_log_date >= '2006-08-07 00:00:00';
ERROR 1054 (42S22): Unknown column 'task_log_creator' in 'on clause'

Switched table names in FROM:
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mysql> SELECT t.*, CONCAT_WS(' ',contact_first_name,contact_last_name) AS creator FROM tasks, task_log t LEFT JOIN users AS u ON user_id = task_log_creator LEFT JOIN contacts ON user_contact = contact_id LEFT JOIN projects ON project_id = task_project WHERE task_log_task = task_id AND task_project = 1 AND task_log_date >= '2006-08-07 00:00:00';
ERROR 1054 (42S22): Unknown column 'task_project' in 'on clause'

Using:
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mysql  Ver 14.12 Distrib 5.0.18, for redhat-linux-gnu (i386) using readline 5.0