To ask Siri " is my brother here yet" your brother has to have FIND MY FRIENDS installed on his phone and allow you to see him,.... I too have IOS 6 installed onto my phone and siri is much better, like she can update facebook/twitter.... open apps.... ask her sports fixures etc.... she can even guide you turn by turn if you ask her for example.."take me to bridge street"?.... she will open maps,plan your route, then tell you to turn in 100yrds etc,... she isnt perfect though and alot more needs to be done... eg.,, I asked her where i can buy petrol and the nearest petrol station programmed in her was 95 miles away!!!
Not perfect but a massive improvement.
Iphone 4s
IO6(beta2)
YoLo