Here's the summary, at least as of the date of that article:
1. The only fully unlocked iPhones are the ones you buy directly from Apple, not from any carrier or reseller (BestBuy, etc.).
2. Your phone may be unlocked for European SIMs but not unlocked for another US carrier.
3. No US CDMA carrier will ever activate an "unlocked" phone previously activated on another CDMA carrier's network.