270mA or even 250mA is way too high.. I get 190mA without any tweaks.. I'm using Overo-Fire and summit hardware.
You can recompile the kernel after enabling sleep while idle or opportunistic sleep in the kernel configuration.
bitbake -c menuconfig virtual/kernel
Also try turning off wifi and usb chips. If you are using overo, this might work straight away for you.
echo 0 > /sys/class/gpio/gpio16/value
Also try enabling cpu-freq flags in kernel configuration, and try bringing down frequency of operation..!
Aim for about 90mA after all this.!! All the best..!! :)