Seems Anet slipped this one past me. Last night when the new match ups went live the following was posted as a sticky in the WvW subforum of the Guild Wars 2 Official forums. I have just now stumbled across it.
For the matchup starting on December 7th we’ll be testing out a new culling methodology. This is an interim change to the system which is intended improve player experience while we work on a more comprehensive solution. Under this new, interim system we handle culling of allies and enemies separately which should cut down on the instances of running into a group of completely invisible enemies. This is accomplished at the cost of having a lower maximum on the number of allies that players can see.
Again, this is an interim solution while we work on a longer term change. We’ll be trying out the new system for the duration of the matchup starting on December 7th and then evaluating whether we want to keep it in place until our more comprehensive solution is in place or roll back to the existing behavior. Toward that end we’re very interested in your feedback about the experience of playing with the interim system. (Habib Loew - Guild Wars 2 Forums)
This has been a problem for quite a while and it is nice to see it finally being addressed. I would have liked to see this announcement in a more prominent position on the main site though. Sneaking this kind of thing into the forums is just cheeky. Mr. Loew continues with this followup:
All players are eligible for boons, etc. because those are calculated on the server. You’re correct that allies who are culled will remain culled until a “slot” opens up for them. That happens when the culled ally is closer to you than the currently shown ally for some small period of time.
The main difference between this and the current system is that the current system treats all characters the same while the new system has one limit for allies and another for enemies. In the new system enemies cannot impact which allies are shown and allies cannot impact which enemies are shown. (Habib Loew - Guild Wars 2 Forums)
Players in your party are always reported to you and are never culled. Guilds are not favored in the current system. (Habib Loew - Guild Wars 2 Forums)
Be sure to report your personal experiences back to the Anet people. Feedback is valuable and I am sure they would appreciate yours. I haven't noticed a difference yet, but I will watching for this now to see if there is a difference.