Cheapest method for content delivering?

Hey, I'm looking to build a blog about funny images n things and I want to use the cheapest method for content delivering to users.

Let's say I get lots of views/days and I can't use basic hosting packages for this (like hostgator $9 one) - Can I use wordpress.com free blogs for content delivery? For example what Icanhascheezburger.com network is using?
Their images link is like this:
hxxp://icanhascheezburger.files.wordpress.com/2011/08/funny-pictures-untitled.jpg

Are they using free wordpress blogs and they just bought a domain for them or they are using a different free wordpress blog just for files? Also is it free to use wordpress free blogs this way?

That wasn't the question, did you read my question?

I agree, if your server goes down cos it can't handle the requests, be happy! Then get CDN (I recommend amazon aws when you do).

Okay so let's say I use the wordpress free hosting option, with a domain name. Can I still modify theme like it was on external hosting or it has the same limitations.

I guess the easiest solution is to have 2 blogs, 1 with free & 1 with hosted WP and just upload things to the free hosting & link from the main blog.

Host your own site on shared hosting, you'll do fine for a LONG time.

If you become immensely popular you will want to have multiple dedicated servers - at that point you will have distinct static and dynamic servers, you will also want to implement some sort of caching. But you won't have to worry about that for a while.

Don't use free Wordpress - it's too limited for business, and the TOS of free Wordpress specifically disallows making any sort of profit with it - it's for hobby blogs only.

And the answer to your original question: Cheezburger is using WordPress VIP - entirely different from the free Wordpress solution, and also very expensive. That service is used by lots of large clients, notably CNN.

Hosting media on Amazon S3 is actually a really cheap fast content delivery method.