The Evernote, Google Docs, and photo upload examples are all very similar - the app starts an upload while the app is in the foreground, then let the app go to the background and finish the task.
That works when all the information can be sent in one contiguous chunk, and is all going in one direction - up to the server.
OmniFocus breaks the information up into lots of smaller files, so you don't have to fetch as much information during any given sync. (You can just update the new bits of information.)
However, this also means that our sync requires two-way communication, and we don't know the complete list of files we by the time the app is sent to the background after you press the home button.
What
this tweet from the lead programmer means is that OmniFocus is saying "hey, iPhone, can you please pull some information down from the web server", but the requests don't actually get sent.
Executive summary: different apps give the same name ("sync") to features that work very differently on the inside. :-)