You can clone with
HTTPS or Subversion.
Connect your pump account to a Github account.
I like this very much. I understand how you could follow on Github your pump.io friends, but how is it going to find all the Github friends that have a pump.io account? Is there a way to signal that on Github? Or does this mean only within the same pump.io server?
Same question for Tumblr.
To find all the Github friends that have a pump.io account, there has to be a service that a) lets you log in with Github and b) lets you log in with your pump.io account. That gradually builds up into a database that maps [Github user] <-> [pump.io user].
It can periodically check your Github account for people you follow, and if there are new ones, start following them on pump.io (and maybe add them to a list so you can keep track of the ones that came from Github).
If you have a friend who doesn't have a pump.io account, and then they get one and sign up at the Github connector, it can instantaneous make follow them (and vice versa).
After having used http://pump2status.net/ I understand the idea better. I will write it down here again in my own words for anyone else who may be confused.
The github-following service is a separate application (a separate server), to which you register using pump remote auth, and then attach your github user using their auth mechanism. If there is only one such service, then it can notice that two github friends are both registered to it, and automatically connect them in the pump universe.