The folks at WordPress.com launched a URL shortening service for all WordPress.com users. They acquired Wp.me domain name for the same and now each and every post of WordPress.com will carry a short URL.
If you blog at wordpress.com you can use of the feature, when you edit or create a post it will display Get Shortlink button, clicking on that link will popup a short URL for that post or page which you share it on sites like twitter. You no longer have to worry about losing your data as they are hosted on WordPress.com. They are claiming that these links will be there as long as WordPress.com is around.
These links are also added to the HTML of the post in the <head> section with rel=â€shortlinkâ€ microformat. For now these links are only available to WordPress.com users, currently self hosted wordpress blogs doesnâ€™t have this feature but this may be coming as the comments in the official post point out.