I'm getting a similar problem as glamgeek when trying to export/import my Posterous blog to my WordPress blog, here's the error message I'm getting:
Fatal error: Call to undefined function: simplexml_load_string() in /home/content/t/r/o/****/html/yourdailydoseof/wp-content/plugins/posterous-importer/posterous.php on line 121
(****= my username)
I'm using WordPress 3.0.1. I don't really want to create another blog on WordPress.com to import to from Posterous and then export to my WordPress.org blog because the reason I created the Posterous blog in the first place was to export my TUMBLR blog...
I know, right? Starting to get a little complicated here. However, I have figured out a work-around to export/ import from Posterous to WordPress:
Posterous has the capability of allowing you to "autopost" to various other platforms (Twitter, Facebook, Buzz and WordPress to name a few; there's about 28 listed). On the "Manage" screen of your blog, click on "autopost" and then click on "add a service" a Flash box will open up and allow you to choose which platform (and your blog address) that you want to autopost to. Choose "WorPress" and enter the URL for your blog.
Once you have that set up, go back to your posts choose one and click on "edit." If you need or want to make changes go ahead and do so now; now click on "autopost" (again, in the right hand column) and another flash box will pop up with the name of your blog. Click on that and boom goes the dynamite, DONE! You have exported your post to WordPress. You may or may not have to edit in WordPress once you get it over there. Written posts look okay but you may have to "center" your pics & vids, the pics & vids I "autoposted" were left-aligned.
NOTE! Your tags and comments will NOT export with the post. Also, it autoposts immediately so you will have to go and set your tags and backdate the post to when you originally posted it for conformity.
May be a little time consuming for most of you but this is probably going to be the best work-around for me- I only have about 100 posts, no comments to worry about and since Tumblr wouldn't let you use tags anyway it won't take me but a day or two to get this set up.
Was really excited to use the Posterous importer plugin but it didn't work for me and it looks like the guy that wrote the code hasn't checked this thread in four months so, going the route detailed above is probably going to be the quicker one for me.
Sorry for being so long-winded but I hope this helps.