I just purchased a copy of Acceleroto's Air Hockey for Palm webOS, which includes the Palm Pre and the upcoming Palm Pixi.
Before I tried to purchase anything from Palm's App Catalog, I chose to enter my credit card information by linking App Catalog with my Palm profile and then entering the card information. Once that was set up, I was ready to purchase my first application. You will be happy to learn that your credit card information is not actually stored on your webOS smartphone. It is stored on a secure server; just like your account information is stored in your Apple iTunes Store account. If you regularly purchase application on your iPhone or iPod touch, you will be at home with purchases from App Catalog on your Pre.
The purchase process was quick and easy and the game was installed on my phone without any trouble. Acceleroto Air Hockey can be purchased from the Palm App Catalog for $1.99. For more information, visit the Acceleroto blog.