The biggest Vitamin D supplements I've seen have 1000 IU per tablet, and the bottle suggests one tablet per day. According to the article you linked, 10,000 IU/day is safe (we can get that much from sunshine in a day), and long-term overdose has been observed at 77,000 IU/day. You'd have to go pretty hog-wild with the Vitamin D supplements to overdose.
For what it's worth, I supplement using the 5000 IU pills taken at about 7/week (irregularly, making up doses as necessary). I recently had my blood tested for D3 levels, and found it was close to but not exceeding the standard recommended level.
That article is just about Hypervitaminosis D, other harmful effects are possible (depending on the individual) when supplementing at high levels like 10,000 IU/day.
