Already implemented

8Mhz CPU for ST and STE modes
16Mhz CPU for Mega STE mode
~48MHz CPU for STEroids mode, roughly as fast as a TT
Up to 14MB fully DMA supported and video capable ST RAM
ROM cartridge support
Support for 256k and 192k ROM images
TOS versions 1.00, 1.02, 1.04, 1.06, 1,62 2.06 and EmuTOS 0.8.7, 0.9.0 and 0.9.1 and probably more ...
All three ST video modes
SM194/Viking compatible 1280x1024 high rez video mode
Scan doubler for color modes for VGA compatibility
PAL 56 HZ for VGA compatibility
Floppy disk emulation via SD card (.ST formats incl. HD (1.44MB) and ED (2.88MB))
AHDI compatible ACSI/HDD emulation via SD card using Hatari compatible ACSI images
MFP (Timers, RS232 redirection, IRQs, ...)
Sound
IKBD emulation (joysticks, mouse, keyboard)
USB mice, keyboards and joysticks
Printer/RS232/MIDI redirection to a PC connected via USB
Ethernec compatible network using DLink DUB-E100
Minimig on screen display (OSD)
Ability to change the core (to e.g. boot into Minimig)
MIDI add-on board
Blitter (Optional for ST, mandatory for STE)
STE video (4 bit per color, hard scrolling, split screen, ...)
STE DMA sound

Planned/Possible

Falcon compatibility (This requires a DSP and various other complex things that don't fit into the MIST FPGA)
68040/68060 add-on board (the MIST doesn't have enough spare IO pins for this)
68040/68060 FPGA implementation (the MIST FPGA is too small for this)

Mega STE and more has been done, parts of a TT are also done but full TT compatibility is very unlikely and Falcon (incl. e.g. DSP) is impossible