Re: the whole publicity stunt thing...
I think we should all remember something - Madonna is currently generating masses of newspaper column inches simply because she has released her best album in a decade, and she's been on an extremely successful world tour.
For someone in her current position to adopt a baby (which she will mother for the rest of her life) as a publicity stunt is...well, madness.
Think about it for a minute! Knowing how media savvy she is, do you really think she'd saddle herself with a child, for a few weeks of headlines?
She's not that stupid.