If you can write your posts in 2 or more(Woo…) languages within one blog, you might want to tell the client browser the language attribute of you posts.
According to <a href="http://www.w3.org/International/tutorials/language-decl/en/all.html" title=" W3C tutorial" rel="nofollow ugc">the tutorial on W3C</a>, language attribute can be declared in the container html tag of your post like this: 
<div id=”post_id” class=”post_entry” lang=”zh-Hant” xml:lang=”zh-Hant” dir=”ttb”>… 
Here “zh-Hans” is the language attribute of your post which means it’s written in Simplified Chinese.
This plugin gives your post a language tag by adding a meta deta to that post.
To add language tag, select it from the language box when you compose/edit a post. Select “None” will delete the language tag.
<h3>Revisions</h3>
2007-12-18, 
0.2: Now you can difine language direction. 
 Insert CSS style into page head automatically to support pretty printing.
 readme file updated for new feature and fixed a error
2007-07-23 
0.1: First release

Multilingual post

This plugin adds a standard compliant language tag to your post and page.

Brian Layman

Word Filter Plus allows you to replace one word or phrase on your blog, with another word or phrase. It can do this passively, by replacing content as it is displayed, leaving your database unchanged. It can do this actively, by updating the content as it is created or edited, leaving the display of your site efficient as ever. It can even update all of the posts or comments all at once, in a server friendly way.
If you need to run the plugin on multiple sites, there is an export and an import feature to save effort and eliminate mistakes.
This plugin will help you clean up your site’s content. In its simplest form, it finds one word you are using and puts in another word. You might want to replace can replace the word “firetruck” with “f**k” or make your “2112 Rates and Fees” become your “2113 Rates and Fees” everywhere that text exists.
The reasons that you might want to do this are many. Here are seven I thought about as I made this plugin:
<ul>
<li>You’ve been told by advertisers they can’t advertise on your site because of the use of high risk words.</li>
<li>Terms that were ok to use one year, are now considered highly offensive</li>
<li>You’ve found you are blocked from schools and homes with content filters that are active.</li>
<li>A lawsuit/DMCA issue has forced you to remove references to a certain topic or company</li>
<li>Your phone number/company name/last name has changed and you want to update it on your site.</li>
<li>You wish to add hyperlinks to every reference of a specific word.</li>
<li>You’ve removed/replaced a plugin and you now have short codes that don’t work and you need to update them all</li>
<li>You’ve reference a year or date in posts or titles and you want your content to appear current.</li>
</ul>
There are other plugins that do similar functions, including the Word Replacer Plugin, which formed the foundation of this plugin. However, the “Plus” in “Word Filter Plus” means that I’ve added a number of extra features. These Plus features include:
<ul>
<li>Passive and Active modes to allow you to temporarily or permanently make the changes to your post content.</li>
<li>Batch mode is introduced already optimized to clean LARGE websites and cause no performance hit upon page load once the cleanup has been completed.</li>
<li>Import and Export features allow you to configure your replacements on one website or even in a spreadsheet and import them into your other sites.</li>
<li>Improved security around both the database access and the settings screens.</li>
<li>Excerpts are now included in the filtered content.</li>
<li>Improved on-screen help content.</li>
<li>Reworked the table structure to allow better default behavior.</li>
</ul>
<h4>Features</h4>
<ol>
<li>Replace one word or phrase with another word or phrase in your posts, pages, titles and excerpts.</li>
<li>Moderate the content others are placing on your website in comments.</li>
<li>Enforce editing standards upon people who are contributing posts to your site before the fact, not after.</li>
<li>Use regex to replace a word when it is used in a specific context</li>
<li>Use regex to parse matching text, extract values and build a replacement text using those variables</li>
<li>Passively filter your content as it is displayed, leaving the database unchanged.</li>
<li>Actively filter your content as it is saved, updating the database once, causing no delays as your content is displayed.</li>
<li>Update all existing content on your site in batches, being friendly to your server.</li>
<li>Create the replacement list in any spreadsheet tool and import it into the site. Or export one site’s settings for import into another,</li>
</ol>
NOTE: Thank you to my daughter Azia for making the WordPress.org Banner for this plugin.

Word Filter Plus

Update or clean the contents of your site, by filtering or replacing words and phrases in your posts, pages, excerpts, titles and comments.

Multilingual post vs Word Filter Plus