It's as good a time as any to push out one of my backlogged SSIS posts. It wasn't any fun jousting with 0xC0047041 (SQLIS) last year, but a little more caffeine put me over the top that night. Heh. You can only stare at the SQL Server 2005 Management Studio so long before you get the urge for another Mountain Dew Live Wire.
In addition to the situations noted on the SQLIS wiki, this also happens when you try to attach the input for component in one data flow task to the output of a component in another data flow task. It's not a problem if you're using the UI provided, but if you're programmatically building packages from templates, it could be one of those smooth developer moves.
Integration Services rocks!