This thread has been dead for 8 years - and it was dead for another 5 before that? Sounds like the perfect time to comment!
The simple answer is: YES, Kira Kener is retired!
Why? She got fired by Vivid. Lawsuits followed, and the ordeal led to Kira's retirement from the adult film industry.
Reputation:
Kira developed a reputation for being difficult to work with. This was in part due to the fact that Kira was uncompromising with her work stipulations. She would not perform certain acts. For example, Kira didn't do facials on film. She was also very selective about who she would work with, and she insisted on using condoms. Early in her career those were non-issues, especially because Vivid was one of the few adult film production companies that was pro-condom. Unfortunately, Kira's reputation for being difficult to work with wasn't strictly limited to her work standards. As Ms Brittany pointed out, Kira had a tendency to be socially abrasive. So it's safe to assume that there were tensions with Vivid leading up to her firing.
Firing:
While filming in 2004, Kira raised concerns about a sex toy being used in the scene. The details are murky, but it seems that Kener complained about having to perform with an adult toy that had previously been used. An argument ensued, and ultimately the director convinced Kira to proceed with the scene. The next day, Kira arrived on set in tears, asserting that she had contracted a venereal disease. She refused to work until the studio promised to get all of her co-workers tested. The studio claimed it didn't have the time or money, and ultimately fired her for refusing to work.
Lawsuit:
Ms Kener filed a wrongful termination lawsuit against Vivid in 2006. Originally, she was seeking $5mil in compensation and damages, but ended up settling out-of-court for the sum of $250,000 in 2007. Unfortunately, the settlement included non-disclosure agreements so we'll never know all of the gritty details. However, Kira has claimed that she didn't receive a dime of that money due to her legal fees, and Vivid defaulting somehow.