I've just been having a conversation with our Assistant head about the best way to introduce Moodle 2 to our staff - ironically over a year sinc I have been doing it in other establishments. I made a course for when I did an Introduction to Moodle session at the UK/Irish Moodle Moot last month and it is available to download from MOOCH - you could use that. It's not for moving from 1.9 to 2 specifically but it does introduce many features and so could be a good recap as well as intro to Moodle 2. You can see it here but obviously can't do the activities or download - http://www.moodlefairy.co.uk/course/view.php?id=39
Oh and - lots of changes have happened since my book came out in Nov 2010 - so I would still suggest you use the Moodle 2.2 documentation as that is up to date