lardconcepts:
Should I jump right in and learn C++11? Can I assume that most of what I'd want to do (ie: not very complex) will be supported by the 1.5 series of the Arduino IDE? Or should I stick to learning older versions?
Well the problem is, the compiler released with the Arduino 1.5.4 beta release is still the 4.3.2 compiler that they've stuck with for years. So, unfortunately, you are stuck at C++98 (well you could populate your own system with the newer compiler, but you wouldn't be able to share your code with the majority of users).