Apparently both Intel and Microsoft think so.
In particular with new C++11 and C++14 features, the language may be usable (enough).
Getting Started for C/C++ (Eclipse) - Galileo & Edison @Intel
NuGet Gallery | Microsoft IoT C++ SDK 1.0.0
NuGet Gallery | Galileo C++ SDK 1.0.6
Another portable alternative, likely to be more popular is node.js (or its new "fork" io.js).
Building an IoT Project with Intel Galileo and Node.js | Dr Dobb's
Intel(R) XDK IoT Edition node.js Templates | Intel® Developer Zone
Apple Swift could be very interesting, since it is both efficient and high-level modern language,
is supported by Apple, with smart people and virtually unlimited resources...
When Apple starts making IoT gadgets, that may be a good choice.
HomeKit - Apple Developer
HealthKit - Apple Developer
Google's Go is less efficient for small devices, and is optimized for parallel programming.
since they could reasonably run on many platforms,
but GC (memory management) makes them less usable for "real time"...