user_roles with features
Is the Role listed on admin/user/roles?  If not, your Feature might not be defining a Role, or the Feature might be overridden.

Roles defined by Features do actually show up in user_roles().  I created a simple Feature defining a single role, then enabled it:

% drush php-eval "print_r(user_roles())"
Array
(
    [1] =&gt; anonymous user
    [2] =&gt; authenticated user
)

% drush pm-enable yayfeature
The following extensions will be enabled: yayfeature
Do you really want to continue? (y/n): y
yayfeature was enabled successfully.                                                                                          [ok]

% drush features-revert yayfeature
Do you really want to revert user_role? (y/n): y
Reverted user_role.                                                                                                           [ok]

% drush php-eval "print_r(user_roles())"
Array
(
    [1] =&gt; anonymous user
    [2] =&gt; authenticated user
    [5] =&gt; yay
)