Well the kid was 1st round talent, the only reason he wasn't drafted till the 3rd was because everyone thought it was a given he was going to college & signability issues. You see he was also a multi-sport athlete, was also a top college football recruit too (if you follow college football, you've heard of his brother who was QB of the Wash. a bit back)
Matt is more advanced for his age then most and also has great tools/make up. Everything I hear has him going to Low A to start the year, after that is really depends on how he developes. You really can't ever predict when someone that was just drafted will be in the bigs, you get a much better idea after their 1st full year in the minors. Personally I think he has the highest potential in the M's system, aside from Felix of course. My best guess would say look for him to be close to the bigs in 2007 or so, if everything goes well.