How To Make Curved and Rounded Text in Photoshop CS4
Curved text

Step 1: First you select the pen tool

Step 2: Then you click pretty much anwhere on the page to make an anchor point
Step 3: Click and hold about 10cm away from the anchor point horizontal to it
Step 4: Still holding the mouse button, drag the next point downwards
Step 5: Now get the text tool and click anywhere along the line where you want to start typing the text and write your message and you are done!
Rounded Text
Step 1: First select the elipse tool
Step 2: Create a circle at the area you want the rounded text
Step 3: Now get the text tool and click where you want to start typing the text around the circle
That is all.

Here is a link for a very short and sharp tutorial http://www.youtube.com/watch?v=m8yaWPC2kwM