Corrine the dev that is leaving GBX is the director of technology. She was talking about the engine coding I think. She's basically saying all the game features now have code and are up and running. Her replacements will be the ones fixing any bugs that will crop up. I imagine the game as a whole still has a long way to go when it comes to level design, building resources for the game etc. I think its only just approaching beta.
And the beta phase is just as work heavy as the alpha stage, if not more so due to all the fine tunning of game mechanics, balancing and testing etc.
Gearbox don't really like to rush bug ridden games out the door either (thank god). So I think we will see a few more release date slips before we eventually get to play this game in 09.