To install App Engine Python SDK for local development, in this directory:
%> wget http://googleappengine.googlecode.com/files/google_appengine_1.6.4.zip
%> unzip google_appengine_1.6.4.zip

AppEngine uses Python 2.5.  To install Python 2.5 locally on a Goobuntu machine:
%> sudo aptitude install libsqlite3-dev
%> sudo aptitude install build-essential gcc
%> cd /usr/local/google/home/$USER
%> wget http://www.python.org/ftp/python/2.5.5/Python-2.5.6.tgz
%> tar -xvzf Python-2.5.6.tgz
%> cd Python-2.5.6
%> ./configure --prefix=/usr/local/python2.5
If on GPrecise, do this step:
  %> vi Makefile
  s|LDFLAGS=|LDFLAGS = -L/usr/lib/x86_64-linux-gnu|
%> make
%> make test
%> sudo make install
%> sudo ln -s /usr/local/python2.5/bin/python /usr/bin/python2.5

A utility script dev_appserver is in this directory to call
./google_appengine/dev_appserver.py with arguments for correctly using
python 2.5 and serving at <yourhostname>:8080 (which can then be
accessed from other machines on intranet).  See contents of script
for details on what it does (it is very short).

Examples based on project name chromiumos-build-stats.

To start the dev server on <yourhostname>:8080 do this:
%> ./dev_appserver chromiumos-build-stats/

To clear DB before starting:
%> ./dev_appserver -c chromiumos-build-stats/

To update on chromiumos-build-stats.appspot.com (WHEN READY):
%> ./google_appengine/appcfg.py update chromiumos-build-stats/