Use default installation profile? I've written a custom installation profile.  When running install.php for the first time to install it, I have to select the installation profile I want to use.  I then select mine and run the install profile, no problem.  However, my client wants to be able to use the profile I put together as the default installation profile and skip that first step entirely (selecting an install profile).  How can this be accomplished?  Simply setting it as the default selected profile is not enough.
This part of your original question isn't quite clear:


  Simply setting it as the default selected profile is not enough.


However, all you have to do is to add exclusive = TRUE in the .info file of your installation profile.
This will automatically select your installation profile, and the user will proceed to the language selection screen.

Note 1: the setting above will be ignored if there are 2 or more installation profiles marked as exclusive. This might happen only if you downloaded another installation profile and are keeping it in the /profiles folder (e.g. Commerce Kickstart).

Note 2: this has been committed to Drupal 7.22 and is based on this issue/discussion.