I sold my MiFi via eBay this week and shipped it out today to its new owner. I had the MiFi for about a year and really enjoyed it but it was usurped by my iPhone 4 and the Personal Hotspot feature that debuted earlier this year in iOS 4.3.
So far, my iPhone has replaced several other things, both digital and analog, in my life. For example, I no longer own a separate iPod (I used to own a 5th-generation iPod video, a 1st-generation nano and an old Shuffle) since my iPhone is my dedicated music player – I have it with me everywhere I go (even at the gym thanks to the Armpocket armband holder).