In the 3.5 version of the d20 system, there is some possible confusion around the Run and Move actions and Attacks of Opportuny (AoO).
(For those readers who don’t like the d20 system or AoOs, I suggest you stop reading now.)
First, there is a general rule: Leaving a threatened square draws an AoO with two exceptions. The first exception is if your only movement that round is a 5 foot “step”. The second is if you are using the Withdraw action.
Second, there are tables that indicate whether an action itself draws an AoO. Here it is indicated that both the Run and Move actions provoke AoOs.
This can be interpreted to mean that entering a threatened square during a Run or Move action draws an AoO. Because, if the first rule covers the leaving case, there’d be no need for the second rule.
On the Wizards’ web site, however, can be found this clarification:
The move and run actions are worth a special note. According to Table 8-2, both these actions provoke attacks of opportunity; however, the basic rule for movement and attacks of opportunity still applies. When you move from one square to another in combat, you provoke an attack of opportunity when you leave a threatened square—not when you enter a threatened square.
(Thanks to Von for finding that.)
So, for me, that makes it clear that Run and Move are in no way exceptions to the basic rule. The “Yes” in their AoO column merely distinguishes them from Withdraw. Just stick to the basic rule. Mostly...
There is, however, at least one exception to the basic rule: Crawling (which is covered by the Move action). Crawling is only a 5 foot move, and it provokes an AoO for both leaving a threatened square and entering a threatened square.