Task points are Batmud counterpart to E2's C! awards. In Batmud you can achieve taskpoints not by playing the game (which gives experience points to the player) but from completing various tasks the wizards of the game have put up for players. These tasks include finding typos and bugs, giving up (good) suggestions to develop the game further and so on. From these tasks players usually get 1-5 taskpoints and finding some really big bugs could give as much as 50 task points but that is really rare.
Batmud is ran by Bat RY which is a non-profit organization and thus charges nothing from players playing the game. Still sometimes even batmud needs money to buy new hardware and pay for Internet connection to ISP. Batmud uses donations as a way to gather money for such expenses. Players donating money to the game get task points in return. Rate for task points has been around 2 taskpoints for 1 euro for small amounts and 3 to 1 euro for higher amounts. Of course the players don't have to donate money to the game while the donations are accepted, but many consider the game so valuable to their life that they are ready to donate quite great amounts of money to support it (some speak of as high as ~2000 euro donations!).
Players with task points can use them into getting boons to their character, such as more strength, quicker spells, more effective skills, more resistance towards damage, more damage and so on. The boons are not 'cheap' to buy with taskpoints as first full boon needs 150, the second 240 and the third 320 task points.