The iPhone 4S has been out for around 10 months, and MAYBE Apple will introduce a new model in the fall (seems likely). But they are nearly dead certain to continue selling the iPhone 4S (and maybe the iPhone 4) as a "new" model for the foreseeable future.
What bogie1519 meant by his remark is that iOS 6, which is also expected to be released this fall, will offer new features that will make any phone that can run it seem new.
By the standards of every-three-days-a-new-model Android, the iPhone 4S would seem old. But by the standards of people who want to use and enjoy a really high-quality phone, the iPhone 4S continues to dazzle like new.