Despite what Gregory Janson said, Megazeux version 3.0 is in the works, although this is very old news. Ultrazeux is in the works as well, I'll add a section for it whenever it comes to be in even the planning stages.

The last update to MZX was 2.51, which was mainly a bug fix, not adding many new features.

Way too many to list. Go to Barney's Megazeux Stockpile she listed them.