An exact ETA is unknown but we do know at least four main areas of focus; GPU "hitching", better Quickmatch and complete server browser results.
The last item on the list is dealing with the "game session is no longer available" error when playing Zombies. The patch last week has helped some but then hindered others according to community rumblings. Treyarch posted the details:
IN PROGRESS
- GPU hitching on certain graphics cards.
- Incomplete server browser results.
- Improvements to Quickmatch joins (results with better ping and reduced lag).
- Zombies "The game session is no longer available" error.
Call of Duty: Black Ops released on Xbox 360, PS3 and PC last week and became the top videogame launch title ever, amassing $360 million in sales day one.