All non-British (Lithuanian) elements like š,ė,ž,č and much more are displayed as code which does not look good. I added a facebook like button to my wordpress blog, which appears like this:

<iframe src="http://www.facebook.com/plugins/like.php?locale=lt_LT&href=<?php echo urlencode(get_permalink($post->ID)); ?>&amp;layout=standard&amp;show_faces=false&amp;width=450&amp;action=like&amp;colorscheme=light" scrolling="no" frameborder="0" allowTransparency="true" style="border:none; position: relative; top: -150px; padding: 0 0 20px 0; overflow:hidden; width:450px; height:60px"></iframe> 

You can observe which i added locale=lt_LT (I am from Lithuania)

DOCTYPE:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

Im by using this:

<?php
    $thumb = get_post_meta($post->ID,'_thumbnail_id',false);
    $thumb = wp_get_attachment_image_src($thumb[0], false);
    $thumb = $thumb[0];
    $default_img = get_bloginfo('stylesheet_directory').'/images/default_icon.jpg';

    ?>


    <?php if(is_single() || is_page()) { ?>
        <meta property="og:type" content="article" />
        <meta property="og:title" content="<?php single_post_title(''); ?>" />
        <meta property="og:description" content="<?php
        while(have_posts()):the_post();
        $out_excerpt = str_replace(array("\r\n", "\r", "\n"), "", get_the_excerpt());
        echo apply_filters('the_excerpt_rss', $out_excerpt);
        endwhile;   ?>" />
        <meta property="og:url" content="<?php the_permalink(); ?>"/>
        <meta property="og:image" content="<?php if ( $thumb[0] == null ) { echo $default_img; } else { echo $thumb; } ?>" />
    <?php  } else { ?>
        <meta property="og:type" content="article" />
       <meta property="og:title" content="<?php bloginfo('name'); ?>" />
        <meta property="og:url" content="<?php bloginfo('url'); ?>"/>
        <meta property="og:description" content="<?php bloginfo('description'); ?>" />
        <meta property="og:image" content="<?php  if ( $thumb[0] == null ) { echo $default_img; } else { echo $thumb; } ?>" />
    <?php  }  ?>

Will it be an issue with DOCTYPE or something like that else?

ok, for like button, use facebook developer page and obtain the code for htlm5 rather than iframe. i made like button in the spanish language a while ago, allow me to check my code. i'll get baack for you.

The word what from the button sets whenever you order a control button from http://developers.facebook.com/docs/reference/plugins/like/ the button must have the word what based on the user. example

js.src = "/ / connect.facebook.net / es_LA / all.js # xfbml = 1 & appId = 250867014982684";

that line where it states you are able to modify for the code es_LA language. This really is html 5.