This TensorFlow is a pre-built binary targeted for Raspberry Pi 2/3 running Raspbian 8.0 or Ubuntu Mate.

Find the python version used by typing the command: python --version

Install the dependencies for TensorFlow:

# For Python 2.7
$ sudo apt-get install python-pip python-dev

# For Python 3.3+
$ sudo apt-get install python3-pip python3-dev

Next, download the wheel file from this repository and install it:

# For Python 2.7

$ wget https://github.com/samjabrahams/tensorflow-on-raspberry-pi/raw/master/bin/tensorflow-0.9.0-cp27-none-linux_armv7l.whl
$ sudo pip install tensorflow-0.9.0-cp27-none-linux_armv7l.whl

# For Python 3.3+
$ wget https://github.com/samjabrahams/tensorflow-on-raspberry-pi/raw/master/bin/tensorflow-0.9.0-py3-none-any.whl
$ sudo pip install tensorflow-0.9.0-py3-none-any.whl

After many minutes... 

Successfully installed tensorflow six protobuf numpy
Cleaning up...

Run a very minimal test case.

root@raspberry:~# python
Python 2.7.9 (default, Apr  2 2015, 16:04:32)
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tensorflow as tf
>>> import numpy as np
>>> print(tf.__version__)
0.9.0