I've been asked a few times where I got all the information behind the different management pack related posts I've done. I actually don't have any more access to documentation than anyone else. I come across this information through www.authormps.com, blogs, existing management packs, etc. Well...then I do have contact with the Operations Manager product group, so that's obviously helped a bit.
For those looking for documentation on management pack authoring though, be patient. I don't have the exact details (and wouldn't be at liberty to share them if I did anyway), but I have it from very good sources that there is complete documentation on the way very soon. I'll make sure to do a blog post as soon as it's available.