can I test if a consolidation is already running before running a new one ?

You can use a wcfEventHandler to listen for a consolidaton and pick up the data unit info. You could then query the TaskActivity framework table to see what is running and return an error if needed. The SQL would look somethign like this:

Select Description, UserName, AppName, StartTime, PercentComplete

From TaskActivity Where taskactivitytype = 11000 and appname = 'GolfStream' and taskactivitystatus = 1000

The descirption field will have the data unit info to compare to the requested consolidation.