Many bloggers are now choosing to move from free blogging platforms to self-hosted blogs, which tend to give you greater flexibility and control over the look and functionality of your site. But what do you do with your old blog, especially when you have put a great deal of time and effort into growing and developing it? You don’t just want it left behind, sitting unloved!
If your blog is hosted by wordpress.com then you can now set up a 301 permanent redirect to your new site for $12 a year. This is great news because any traffic headed for your old site will be pushed straight through to your new one. It also means that anyone who subscribes to your blog through Google Reader will still receive your updates.
Setting up the redirect is very simple. Log into your wordpress.com account and click on the Store tab from the left hand menu. One of the options that comes up will be Site Redirect. 
Click the Buy now button. Next you will be asked the URL that you would like to redirect your site to (i.e. your new blog address).
Follow the simple checkout process and then your redirect will be in place. To check your redirects you can go to Store then click on the Domains tab.
If you get stuck, then wordpress have written a guide to help you through the process.
Don’t forget that the charge for this service is an annual one, so remember to renew it each year before it expires. I’m sure wordpress will remind you though.
Just what i was looking for, thanks for posting it.
Excellent, glad it has been helpful!