[Andreas]

It's actually $vbulletin->userinfo['usergroupid'] (for Primary Usergroup) and $vbulletin->userinfo['membergroupids'] (for Additional Usergroups).

If you just want to check if a User as a member of a given Usergroup:

PHP Code:

if (is_member_of($vbulletin->userinfo, X))
{
// do smth.
} 


You can also check several Usergroups at once:

PHP Code:

if (is_member_of($vbulletin->userinfo, X, Y, Z))
{
// do smth. if User is in X, Y or Z (non-exclusive!)
}