This news isn't as big as everyone makes it out to be I think.
Zynga is a rubbish company. They blatantly copy games all the time and have terrible customer service.
Besides, They don't even accept bitcoins for their most popular games : Farmville(edit: I was wrong) and Online Poker.
Doesn't matter how well ran the company is or isn't.
The main point here (at least for me) is that a company that has large profile company people know about has added their name to the list of bitcoin merchants. That's good for bitcoin getting more exposure and adoption, regardless if zynga collapsed tomorrow or not.
It's also a good indication that the gaming industry in general is getting ready to accept bitcoin. Many people have speculated this for awhile since a big chunk of revenue in gaming comes from microtransactions via in game purchases. Companies tend to mimic each other actions, so bitcoin being an additional payment options in gaming seems to be a trend that will be coming in the coming months.