HiddenHelper for iOS
Note: You must be jailbroken to use this.
There is a I suppose pretty use for tweak for free in Cydia called HiddenHelper.
This tweak actually makes it so you can not see the Siri interface at all.
So, say that you wanted to ask the weather you would be able to talk to Siri while on the same screen.
Also, it is worth mentioning that you can set Siri as to if you want to see the answers she gives you and stuff she does for you.