Anyway, the future of professional social networks is destined to be rich ones for each profession/vertical, not the "crappy/high noise for everyone" linkedin model.
I know I'm focusing more on crunchbase[0] and angellist[1] APIs for my startup.
However, at this point crunchbase is pretty open (to the point of giving data dumps) so I'll give them the benefit of doubt for the next 2 years.
Anyway, startups seem to tend towards closing off access to their data as they become the dominant player so it's a question of when not whether.
However, this is great news :) It will just make linkedin irrelevant quicker. They are moving away from being a social network for professionals to being a source of sales intelligence. Most users wont be too happy with that. And, unlike facebook, linkedin is much easier to migrate off of. Really, linkedin was the first big professional network, not the last one.
IMHO angellist is more in line with what the future of professional networks is.