We didn't change anything with the update page in the last code push, so I really can't think of anything that might cause that. The only thing that tries to "phone home" once the page has finished loading is a small piece of JS that saves a draft every 20 seconds (I believe) once you've started typing, but that's the same code that runs on LJ's update page -- we haven't changed it since April, and even then it was just a tiny bugfix, not a big change.

I'm sure Mark will have more useful suggestions for debugging, since I Am Not The Geek(tm), but maybe try looking at a network traffic sniffer to see what's going on in more detail? Alternately, if it only happens in one browser, it might be a plugin or some other helper application that's trying to do something. (We particularly find that a lot of the Firefox plugins designed for LJ can cause weird problems that nobody can diagnose.)