Checking against network-manager-0.9.3.995+git201203152001.04b2a74 in Ubuntu as well as the master in git, I see that NM would treat any NIC names resulting from having biosdevname enabled (of the form em* and p*p*) as wireless interfaces. This is apparent from src/settings/plugins/ifnet/net_parser.c and src/settings/plugins/ifnet/connection_parser.c.

(http://cgit.freedesktop.org/NetworkManager/NetworkManager/tree/src/settings/plugins/ifnet/net_parser.c#n156)
init_block_by_line in src/settings/plugins/ifnet/net_parser.c:

        if ((conn = get_connection_config (pos)) == NULL) {
                if (g_ascii_strncasecmp (pos, "eth", 3) == 0
                    && strlen (pos) == 4)
                        /* wired connection */
                        conn = add_new_connection_config ("wired", pos);
                else if (g_ascii_strncasecmp (pos, "ppp", 3) == 0
                         && strlen (pos) == 4)
                        /* pppoe connection */
                        conn = add_new_connection_config ("ppp", pos);
                else if (ignore_connection_name (pos)) {
                        /* ignored connection */
                        conn = add_new_connection_config ("ignore", pos);
                } else
                        /* wireless connection */
                        conn = add_new_connection_config ("wireless", pos);
        }

(http://cgit.freedesktop.org/NetworkManager/NetworkManager/tree/src/settings/plugins/ifnet/connection_parser.c#n2908)
get_wired_name in src/settings/plugins/ifnet/connection_parser.c:

                gchar *conn_name = g_strdup_printf ("eth%d", i);