I had to move web hosting for one of the WordPress based website recently and once on new server, there are many things that may create problems that need to be fixed. One of the issues is that its media/images uploading starts giving following error:
"your image.jpg" has failed to upload due to an error Unable to create directory /home/accountname/public_html/wp-content/uploads/2011/03. Is its parent directory writable by the server?
Its solution is quite easy, just go to WordPress Admin Panel > Settings > Media and update “Store uploads in this folder” and put “wp-content/uploads” there. You need to remove “/home/accountname/public_html/” from the full directory path.
If it does not resolve the error, make sure that your wp-content direcotry has “755” permissions. If not, then you can easily chmod it to 755 using your ftp client.
Hope that helps.