Clearing Dalvik Cache without root?
I finally figured it out, here's how I did it:  

Even though adb can't get root, and the phone it's self can't get root, as it turns out, there is in fact one more way to clear the cache without fully booting the phone.


Turn the phone off
Make sure you have fastboot working on your computer
Press the power button on the phone and then hold down the volume down button until you see fastboot, then hit the volume up button.
Open a terminal window, and type the following

sudo su
fastboot erase cache



And (apparently) voilà!  The cache is cleared!!