yes, I know that many cameras has built-in HDR mode. iPhone has it too. But because you cna't select a metering point for correct exposure, they sucks at many lighting conditions.+Ken Shelton
For the best quality I use 2 "as-is" exposures from pro HDR an merge them in photomatix and Photoshop, like I do with canon shots.
But this is too much of processing for most smartphone shooters:-)