I noticed that in order to deal with UTF-8 texts, without having to recompile php with the PCRE UTF-8 flag enabled, you can just add the following sequence at the start of your pattern: (*UTF8)
for instance : '#(*UTF8)[[:alnum:]]#' will return TRUE for 'é' where '#[[:alnum:]]#' will return FALSE
found this very very useful tip after hours of research over the web directly in pcre website right here : http://www.pcre.org/pcre.txt
there are many further informations about UTF-8 support in the lib
hop that will help!
--
cedric