As occurring more often something simple is not so simple in SSIS (v 2008)
Situation before B.I. came in: data was loaded into linked tables in hidd
The trick when the GUI doesn't let you do something in SSIS is to tell it you know what you are doing. ;)
In this case, the drop down does not allow you to select values from a hidden tab. The connection manager points to a Excel file with 2 tabs, Sheet1 and Hidden which is hidden.
It does however allow you to select "Table name or view name from variable" or "SQL Command." This solution will use the variable approach but command should work just as well.
As you can see, I have defined a variables called SheetName and assigned it a value of Hidden$
Sample data flow
Results
Progress: 2011-11-07 07:49:32.80
Source: Excel Destination
Cleanup: 100% complete
End Progress
DTExec: The package execution returned DTSER_SUCCESS (0).
Started: 7:49:30 AM
Finished: 7:49:32 AM
Elapsed: 2.121 seconds