I recently moved my wordpress install to a subdomain. And it's working fine, I can post, etc.
Or at least I thought so. I tried to upload an image today and found that it uploaded the file, but couldn't display it.
The website is at blog.gideonaddington.com and it'll show that, even though the subdomain is referencing gideonaddington.com/blog.
WordPress is uploading into gideonaddington.com/wp-content/uploads/... instead of gideonaddington.com/blog/wp-content/upload/...