Yup, it flamed out. It's toast.
Now, there are plenty of reasons given out there why it failed: liberals already have two of the three cable news networks, all the newspapers, and NPR to boot. Plus, Air America simply sucked.
But I think it failed because they wouldn't let any non-leftists on, not guests, not callers. It was a Johnny One-Note thing, and even liberals had to get sick of AA's 24/7 cant.
Center-right positions do just fine on the battlefield of ideas, and if Air America had been anything resembling open and professional, I'd have listened to it myself, cheering for the good guys, of course. But nobody goes to a store that only stocks one item.