It's a reasonable question. The value of data leaks is hard to...

It's a reasonable question. The value of data leaks is hard to quantify for such a diverse range of possible IoT use cases.
I'd theorise that the standard mechanisms are in place: encrypted data packets and secure http (if that is what they're using).
Combine that with standard enterprise per-tier auth and access control and you'd be on par with what even financial institutions use.
The interesting possibility is that the IoT aggregation points could even feature a hardware identity component. Not sure what that would signify re: security. Will have to think more about it.
I'd be more worried about bad data injection TBH - if you have physical access to sensor or aggregation point you have an attack vector. Given that IoT intends to use a distributed assortment of sensor points placed who knows where the attack surface is potentially huge!