SPRING ATTACK [GENERAL]
You are trained in fast melee attacks and fancy footwork.
Prerequisites: Dex 13, Dodge, Mobility, base attack bonus +4.
Benefit: When using the attack action with a melee weapon, you can move both before and after the attack, provided that your total distance moved is not greater than your speed. Moving in this way does not provoke an attack of opportunity from the defender you attack, though it might provoke attacks of opportunity from other creatures, if appropriate. You can’t use this feat if you are wearing heavy armor.
You must move at least 5 feet both before and after you make your attack in order to utilize the benefits of Spring Attack.
Special: A fighter may select Spring Attack as one of his fighter bonus feats (see page 38).
BOUNDING ASSAULT
You can move and attack with superior speed and power.
Prerequisites: Dex 13, Dodge, Mobility, Spring Attack, Base attack bonus +12.
Benefit: When using the Spring Attack feat, you designate two foes rather than one. Your movement does not provoke attacks of opportunity from either of these foes. While using an attack action with the Spring Attack feat, you can make a second attack with a -5 penalty. You can use both attacks against one of the opponents targeted with this feat, or split your attacks between them.
仔细看了下原文，发现Spring Attack翻译本身就不够准确，然后后来那个Bounding Assault也跟着不准确。注意到两者都提到攻击动作(attack action)，特别是后者，是在一个攻击动作中额外增加一次攻击。
因此，我以为正确的理解是：
跳跃攻击：可以在每个攻击动作前后移动，并且不会受到来自被攻击者的AO。
分击脱离：可以在每个攻击动作里增加一下攻击，该攻击受-5减值。同时你指定两个人（一个是你攻击的那个），它们俩没法AO你。
因此分击脱离就可以double你的攻击次数了。
此外PHB2还有后续专长疾速闪击(Rapid Blitz)，可以承受-10减值做第三次攻击，效果是类似的。如下：
RAPID BLITZ
Prerequisites: Dex 13, Dodge, Mobility, Spring Attack, Bounding Assault, Base attack bonus +18.
Benefit: You can designate a third target for your Spring Attack feat. In addition to the second attack you gain from Bounding Assault feat, you can make a third attack with -10 penalty.
再看双武器跳跃攻击。
Two-Weapon Spring Attack (Ex): When a 5th-level tempest makes a spring attack, she can attack once each with two different weapons as an attack action. The character loses this ability when fighting in medium or heavy armor.
注意到，这里也是攻击动作。因此和分击脱离一样，每个攻击动作都可以打两下。
双武器跳跃和分击脱离叠不叠呢，或者说能不能每个攻击动作打三下（前两下双武器，最后一下额外-5）呢？……个人觉得没问题，因为都是在攻击动作上做额外的动作而已。
