MOI is shorthand for Mercury Orbit Insertion. Currently scheduled for March 18, 2011 at 0045 UTC (that's March 17, 2011 at 1845 MDT).
Per the spacecraft's website, a webcast starts at 1755 MDT...my guess is that this will be the only live coverage of the event. Also available on the website, under "Animation", are two Quick Time movies...the quality is LOTS better than the animations of anything Apollo...waaaay back in the day.
Or, dear reader (if any), if you are hopelessly addicted to Orbiter...then download the scenario pack I just uploaded to Orbit-Hangar. This is a "little" more interactive. Plus you get the opportunity to totally FUBAR a multi-million dollar spacecraft (simulated...of course).
A screen shot from the scenario: