One new feature in Mafia Wars is the boost. Also, a new Cuba tier was added - El Cacique. I'll cover boosts in this post, Cacique in the next. Boosts are consumable power-ups that give you added bonuses, for example +5 attack when fighting or energy reduction costs for jobs.
You can get them two ways. The simpler ones can be bought by going to Inventory, then "Boosts". As of now, you need to be in New York to buy boosts, they are not sold in Cuba (yet). I am assuming they will put more purchasable boosts in. This is a needed change because it actually gives Mafia Wars players something to do with their virtual cash. Here are some pictures:
That is an example of some the three boosts you can buy not more than 20 per day. The more powerful boosts like this one are the result of turning in collection items. You can re-vault a collection to receive a number of boosts. This number appears to vary from collection to collection (but it not a random number).
Boosts are automatically used if you have them. . There is a different set of boosts for each collection. Here is a complete list: