The last days I got the request, how to get the contributor permission level in a multilingual environment. Under these circumstances, the name of the permission level depends on the language, in which the site was created. It seems, this is very simple. You may use the SPRoleType enumeration to do the job. To get the role definition you need just one line:

SPRoleDefinition contributorRole = web.RoleDefinitions.GetByType(SPRoleType.Contributor);

Really simple to get these standard roles.