Is it ok to rehome a pet?

Over on Passive-Aggressive Notes, Connie, a cat owner, asks coworker Brian for help in finding a new home for her cat, as she is moving to an apartment where she feels her outdoor cat would not be happy. Brian responds by writing an email to their fellow coworkers accusing Connie of abandoning her cat, who will “probably end up in a shelter” anyway. Then, many many commenters side with Brian, stating that Connie is a horrible pet owner, is abandoning her cat, and that pets are a lifelong commitment that one cannot give up simply because life circumstances change.

So I put it to you, good Jellies. Are pets a lifelong commitment? Is Connie abandoning her cat, and seeing pets as disposable? Are there acceptable circumstances for giving up a pet, and non-acceptable circumstances?