So many gun retailers and makers are offering new guns along with preban mags, and there is nothing illegal about that. The only mags that you cannot own or buy have the restricted LE only markings clearly stamped on them.
There is nothing in the law restricting imported high cap mags (Feinstein wants to fix that) nor is there any restriction on selling US-made preban mags (she'll fix that too).
Feinstein can do whatever she wants, but it doesn't mean a hill of beans until George W. Bush signs the renewal into law. (Which he has promised to do when the bill reaches his desk)
So, in reality it'll be Feinstein and Bush who'll be fixing these "loopholes."
Mostly true. I have read that some mags made after the date have no markings, but even though owning one is technically illegal I can't imagine anyone trying to make a case on that (I mean, we're not psychic). Others just have a date stamped on them. But yes, by far the majority of mags by reputable manufacturers are stamped for LE use if they are restricted. The main thing a buyer needs to look out for is unscrupulous dealers at shows selling mags with the LE Only lettering sanded off. This does happen.
I mainly buy standard-cap mags (as opposed to the postban crippled mags) from places I trust: Cruffler.com, Dillon's Blue Press, etc. BTW, Dillon's has some nice new-in-wrapper steel 30 rd AR-compatible mags from England.