I've been on the leader board for a couple of years, and I do get plenty of random requests about starting HN meetups (I host Hackers and Founders -- Silicon Valley ). I also get a number of random pings to give feedback on people's sites, which I'm generally happy to do.

That being said, I've never been approached to submit a post.

It doesn't matter how much karma you have though - the top users were probably targeted because the leaderboard was a convenient list of active users.