I have a jailbroken first generation Apple TV running the latest firmware (3.0.2), a MacBook with the latest version of Lion (10.7.4, and iTunes 10.7), and an iPhone 5 with the latest version of iOS (6.0.1).
On my Mac, when I click the airtunes icon in the bottom right, all 3 of the airtunes speakers in my house show up (2 of them being airport expresses and 1 being the apple tv); however, when I click the airtunes icon on my iPhone, only the two airport expresses show up and no apple tv.
I have already tried updating the firmware of all the routers in my house (time capsule, the airport expresses) as well as restarting my modem, but it still doesn't show up. It doesn't seem to be a networking issue because I can control the apple tv from the remote app on my phone, so it is obviously being discovered.
How can I stream music from my iPhone to the apple tv? Is there a "hardware limitation" in iOS 6 that keeps me from doing this? If so, is there a way around this, possibly a jailbreak add-on?