Smart URIs in Comment Forms?

Many blogs have taken to posting notices to remind commenters to use HTML to include URIs in comments rather than simply typing or pasting the full URI out in the comment box.  (For example, read the comment form at Outside the Beltway.  See also a long post on the subject at Balloon Juice.)  This is because most blogs designs feature fixed-width comment areas that “break” if the URI is too long.

Obviously, it’d be best if the commenters did use HTML when posting links, but many won’t, because most Internet users remain HTML-illiterate.  The worst way to handle this problem is to put a hold on posting all comments with a URI included and manually edit each comment to make the links correct.  Another way around the problem is to make the comment form a WYSIWYG box, thus making inserting URIs as painless as possible, but doing so increases server load, especially for highly-trafficked blogs.  A better option, which I’ve been thinking about after a couple months of miniblogging on Twitter, where short URIs are a must, would utilize the shortened URI feature of TinyURL!, Snurl, or similar services.

I got to thinking:  WordPress and Movable Type already convert simple characters to special characters after we post — two hyphens become an em-dash, straight quotes become curly quotes, and so on — so why not have “smart URIs”?  The blogging application could catch the presence of URIs, check their character length, and then automatically convert all URIs over a certain length (e.g. 25 characters) to a shortened URI using an API from one of the short-URI web applications or a custom-built app.  Ideally, the blog would combine these short URIs with a link previewing feature so that no one gets suckered into going to a non-worksafe URI, making the links created truly smart.

If someone has already done this as a plugin, then great.  But it really should be a standard feature of WordPress and Movable Type in the future.