Gorsh! That's right! Moodle 2 was released without resolving that little item, wasn't it..... See, http://docs.moodle.org/en/Backup_2.0
Frankly, I have to argue that 2.0 is not suitable for a production environment. Perhaps 2.0.1 will be, but we shall see.... As long as there is no vettable processs to restore 1.9 courses to Moodle 2 it is arguably dangerous to upgrade..... though what does suggest itself is to set up a barebones moodle 1.9 install that will upgrade, and then upgrade the install with one course at a time, then backing that course in 2.0 format and restoring a course at a time to your production 2.0 environment.
How bout you and me going into business to do that - lol. We can set it up via scripts and paypal and suck a pile of money out of les pouvre petites to do what Moodle 2 should have been able to do....
p.s. the journal module now has a new maintain, David, and it looks like upgrading to Moodle with with 1.9 journals and then installing the journal module may be an upgrade path, if the upgrade doesn;t bork, as David and others report some success there..... though I am still suspiscious about whether anything gets orphaned in the process and whether things will play well in the gradebook.... see the thread about this in the contrib journal forum forum http://moodle.org/mod/forum/discuss.php?d=158766