Had probs. at first with the xmlrpc.php file. I thought it was permissions but wasn’t. If you want to post from Writely to your WordPress blog and have more than one blog on your server that uses the same WordPress username to post to both (which I do!), you will need the information from the Writely user forums that I point to in the below link.
The trick is to leave the Blog ID/Title blank in Writely blog posting settings. Simple!
Fix for Writely and WordPress xmlrpc.php when multiple blogs/one name used – http://forum.writely.com/showpost.php?p=431&postcount=6