Not to hijack the conversation, but adding some color commentary. Earlier this year I built a chassis w/ power and networking to power up to 5 PI 2s hanging off the back of the LCD to work on Einstein@Home work units. This was quite successful, and will be even more so when I upgrade everything to Jessie (no more compiling BOINC, etc). Of course when the Zero came out, I had the same desire to build a "cluster" for the same purpose - even if it's not as powerful, it would still look awesome sitting on a desk.
At first, this seemed pointless given all the extra peripherals you had to acquire, but when I came across the USB Gadget guides, I thought the problems were solved! To start, I created a Jessie Lite card, installed boinc-client, input my E@H Key, and away the little guy went. Initial impressions were good - <45C temp at full CPU utilization, and an estimated time to completion about 10% greater than what a single Pi2 core can do. Unfortunately, this has not been a smooth journey.
I'm currently attached to the Zero using a USB/TTL adapter and using the official RPi WiFi dongle with an OTG cable. It is powered with a 1A USB Power supply showing 5.02V. The Zero at full CPU utilization and WiFi powered is drawing between .2 and .25 A. Within the first three hours of operation at full CPU utilization, the machine locked up w/ no logs. After a hard reboot, the machine continued its efforts but it eventually ran in to an issue where syslogd was fighting BOINC for CPU (taking up 50% of the CPU). Another hard reset, I left it running overnight. I woke up this morning to find a kernel panic in the terminal (saved for later investigation).
There are many variables at play - power (shorter USB cable, higher PSU Voltage), trying a different Zero board, building BOINC from scratch, some other unknown configuration item. I will likely start a new thread to follow along in my adventures. I have my first Zero sized powered 4-port USB hub arriving today, and I have been designing a chassis to 3d print for the whole shebang.