Okay. I'm going to offer some advice then I'm walking away from this thread. I'm juvenile but not enough to get into a pointless pissing match especially when I'm not the one getting pissed off here.
The martian line was a good start, but seriously lay off the humor. I mean, really, grandmother jokes?
Here goes. Your blog, is it running on Apache? I'm asking because apache on a *NIX platform keeps it's logs usually /var/log/apache2. My background is with *NIX so that's my point of reference.
You can double check by looking in your Apache conf file for something like
CustomLog /var/log/apache2/access_log combined
You've got a good backup so that gives you a time frame to start from. Look through your access_log and error_log for entries past that time. The search engine bots usually have easy to spot user agent so you can ignore those.
Look in both files for anything abnormal. You know what your blog URLs look like so ignore those. Look for anything that looks like it has embedded scripts in the URL request.
That'll cover the web server.
Now look in your mysql server's my.cnf file and find log and log-error file locations. Look for anything that indicates any problem. I don't use phpmyadmin so I can't point you to where that would log it's actions.
Take a dump of your database and comb through the wp_posts and wp_comments tables. Make sure that some spammy links or code did not get inserted there.
Now head to the filesystem. Take the file listing of the http://wordpress.org/latest.zip and compare that with your files on your blog. Aside from the portions you've uploaded in wp-content, does anything stick out as "Hey what's that php file doing there?"
That's it. If you can't tell what happened after examining your own system, or you can't find anything to add to this thread, then odds are really good no one else will be able to.