I know this has been requested many times in the past - in the Cubase 7 features request forum, and even earlier. Anyway, here is another vote for this feature to be added.
Imagine you’re automating effect sends. You want different reverbs in the chorus, and in the verse. You automate the send so one verb is only active during the chorus. Then you copy the automation, and invert it, and now you can make the other verb active only during the verses.