I like the distinction made between sign-up-friction and onboarding, in that the former is essentially about the sign-up process (i.e. forms). However, it's too bad all of the bad practices listed at the end have to do with ugly, shitty forms.

Going back to how the OP defines onboarding, it's: "*the process of getting a new user to a must have experience and a set of best practices to get them active"

If one of the best practices is to make it easy to upload contacts, then I think it's worth mentioning in the "bad practices" section that uploading contacts unexpectedly, a la Path, can turn users off very quickly, despite your best intentions. Even when users agree to let apps access their phone book, they still don't perceive the kind and quantity of info they're giving out...and so to get an email from some obscure person on their contact list who tells them they don't give a fuck about how said person joined Path...well, that causes a freak out, as we remember well:

http://mclov.in/2012/02/08/path-uploads-your-entire-address-...

Twitter is an interesting example of an onboarding quandary...I agree with the OP that the signup is well-done and slick, however, talking to people who have joined Twitter and then stopped using it...the problem is that new users (especially journalists who are used to thinking everyone is paying attention to them) get turned off by the lack of response when they first start tweeting. This is not the user experience they get on Facebook, when you generally have "friends" right away and are able to "Like" and communicate with them right off the bat.

I'm not sure what the answer to this Twitter problem is, just noting that there's huge room for improvement in that aspect of onboarding.