PiTFTs are awesome! But, to rotate the display you still need to modify the configuration files and reboot. I searched on the Internet for a while and I could not find a way to rotate the display on the fly without rebooting, until now.
Works as of 25/6/15
Just type these commands to rotate the display:
sudo rmmod fb_ili9340
sudo rmmod fbtft_device
sudo modprobe fbtft_device name=pitft rotate=90 #replace 90 with the rotation angles 0, 90, 180, 270
To recalibrate the touchscreen according to the rotation, just type this:
sudo adafruit-pitft-touch-cal -f
That's all. Thanks for reading.