So I have set up a simple server running debian stable (squeeze), and have configured git.
Using gitolite, I have all functionality (at least the basic clone/push/pull/commit) working.
Installation of gitweb went without any issues. However, when I access gitweb, I get a gitweb screen without any repos listed.

# tail -n 1 /var/log/apache2/error.log
[DATE] [error] [client IP_ADDRESS] fatal: Not a git repository: '/var/lib/gitolite/repositories/testrepo.git'

# cd /var/lib/gitolite/repositories/testrepo.git
# ls
branches  config  HEAD  hooks  info  objects  refs

Here is what I see in /var/lib/gitolite/projects.list:

testrepo.git

And in /etc/gitweb.conf:

# path to git projects (<project>.git)
$projectroot = "/var/lib/gitolite/repositories";

# directory to use for temp files
$git_temp = "/tmp";

# target of the home link on top of all pages
#$home_link = $my_uri || "/";

# html text to include at home page
$home_text = "indextext.html";

# file with project list; by default, simply scan the projectroot dir.
$projects_list = "/var/lib/gitolite/projects.list";

# stylesheet to use
$stylesheet = "gitweb.css";

# javascript code for gitweb
$javascript = "gitweb.js";

# logo to use
$logo = "git-logo.png";

# the 'favicon'
$favicon = "git-favicon.png";

What is missing?