Well, I thought I would start this, as I had already been talking about various universes within the Marvel Multiverse, on other threads.
Back in 2001-2002, I saw the "Ultimate Marvel Team-Up" series at my local store, and it looked pretty cool so I bought the whole series. It was not until 2004-2005 when Marvel started to release one-shot Handbooks that I realized that Ultimate Marvel was totally separate from the "mainstream" Marvel Universe, designated "Earth-616". Anyway, upon doing research, I discovered that the Ultimate Marvel Universe had debuted in 2000 as an attempt to "reimagine" Marvel Comics as a whole. Like I said, I did read the Ultimate Marvel Team-Up series, but other than the two "Official Handbook Of The Ultimate Marvel Universe" titles, as well as the "Ultimate Secrets" one-shot released in 2008, I have not chosen to buy any other comics in the Ultimate Marvel line.
So there it is. I wonder if anyone else will add to this conversation. Perhaps later in the New Year.
Happy 2011, everyone!