I assume he realizes that anything of the form "poor man's x" is extremely dangerous. Microcomputers were once the poor man's computer, video the poor man's film, etc.
On some level Google was, for me, a poor man's internet. My initial use of it for months was for the cached pages which would actually load on my terrible Packard Bell with dial-up in 2000.
I don't think he's being disparaging, but it was definitely an interesting choice of words
From a technological point of view, I think he's spot on. However, from a technological point of view I don't think any of what we've seen in the last ten years is really groundbreaking. Facebook doesn't really bring anything new to the table outside of maybe scaling; it ties together all the social connectivity that the Web can offer and makes it available to the common person. We're seeing services package up the technology and provide it to the average person, who now has access to the Internet. Twitter absolutely could have been done ten or twenty years ago (given a platform, of course), but no one had the idea and few could use it easily. That's the key.
That makes no sense. A: Email is free already so who needs a 'poor mans' email? And B: Twitter is nothing like email in terms of it's function and use.
It'll do in a pinch, though -- e.g., when Gmail is down.