This is a real problem and the solution of downgrading / upgrading libxml2 is just impractical for the thousands of us who use hosted ISP services.
My ISP reports that the libxml2 version on my server is ibxml2-2.6.26-2.1.2.7. This is older than the one in question, but it still gives me the same problem. I've downgraded my wordpress version right back to 2.5 with no benefit at all.
This problem relates not only to WLW, but any third party remote blogging software that accesses WordPress through xmlrpc.php
Assuming that this will be fixed by someone with much greater technical competence than I have, I have adopted a workaround.
I've opened an account at Wordpress.com and post to that successfully with WLW and all my third party blogging software (Iphone etc). I then suck my posts back onto my own site automatically using the wp-o-matic plugin and have it transfer my posts through an rss feed.
Perhaps this idea might suit you until this issue is fixed.
Bruce Wilson
