Unboxed my new Arduino Micro (from Mouser Electronics, Made in Italy not a knockoff).
Power up and Pin13 green LED lights and pulses up and down in brightness (like PWM) every second for about 10 seconds, then the green LED blinks on/off 4 times, goes out and then blinks 4 more times, over and over again. The 4th blink is longer than the other 3, then a pause before repeating.
Also my PC does not show the USB device (Win7).
Is this an Arduino Micro (bootloader) error message, or ?
Did you read this?
You may have to install a USB device driver.
Thanks Nick. I made some progress:
It is a bad (power only) micro-USB cable and Win7 USB driver quirky install (different from the FAQ).
(Win7 x64) Start-> Control Panel-> Hardware->Device Manager "Other Devices" - tab is not there. Used a different micro-USB cable and then the tab shows up 
Seconds later Windows reports the driver install failed, and Device Manager "Other Devices" tab disappears.
Disconnect/reconnect the USB cable and now Device Manager "Ports" tab shows "Arduino Micro (COM14)". hurrah.
Tried to upload an old sketch but error messages about timer2 TCNT2 register so I have more work to do. I'm used to the ATMega328, not 32U4.
The Micro has the same built-in USB chip as the Leonardo, Esplora, one of the Megas, and the Lilypad USB version. These USB chipsets are problematic. If you figure out how to program any one of the above, great. If you have any one of the above but can't program it, don't try the others unless you do figure the one out.
Try that link someone else posted if you use Windows or a Mac to get the needed device driver. If you are using Linux you'll have to try different distros or different versions of a given distro until you hit the jackpot. It's supposed to work on Linux but it's a crap shoot.
And don't get me started about the RFduino....