No long words for Posterous. It's cool, it's great, it's life streaming. As a professional bloggers you probably would not find it as a best fit, but it doesn't mean anything actually.
Whatever, back to our problem. I used to have an old blog running at Jroller (http://jroller.com/whiteprohorenko). Jroller http://jroller.com is a traditional hosting site which runs Roller Weblogger http://rollerweblogger.org/project and has a great Java developers community in and around it.
It does support MetaWeblog API, however, Posterous import was failing trying to authenticate it and never started the process.
I got back to Sachin Agarwal and was pleasantly surprised with prompt response from him (I'm getting used to that already ;). He told me that Posterous needs RSD (Really Simple Discovery) to be there to let the process start.
While I am not sure about how things are supposed to run on Roller Weblogger platform and on Jroller, I decided to take a simple workaround here.
First, I create a simple rsd.xml in one of the public folders (you can choose any one, but make sure you have a direct and publicly available URL to it):
<?xml version="1.0" encoding="UTF-8"?><rsd version="1.0" xmlns="http://archipelago.phrasewise.com/rsd">
<api name="MetaWeblog" blogID="whiteprohorenko" preferred="true" apiLink="http://www.jroller.com/roller-services/xmlrpc" />
whiteprohorenko here is the name of my Jroller blog. You need to modify it to fit yours, if you don't want to import mine. ;) However, you will also need to authenticate against it later (as far as I know).
Second, you need to tweak your Jroller blog template to include a correct meta data to point to this "fake" RSD. You can do this from your Jroller settings. Here how should it look like:
<link rel="EditURI" type="application/rsd+xml" title="RSD" href="http://prokhorenko.us/white/tmp/rsd.xml" />
Once again, you need to put your own link here. Basically, that's it. Go ahead to Posterous import page, put a link to your blog here (http://jroller.com/whiteprohorenko in my case), your username and password and go for it.
Boom! Here it is. You can merge your posts (as I did), and you can see old ones here at http://iwhite.posterous.com/?page=24
Have fun and enjoy Posterous.