Hi! This is my first tutorial. I hope you like it 
You will learn here how to do that effect:

You can make that in tutorial below or you can download video tutorial made by my friend (thanks to dura007k
) .:
ownload tuto::.
OK. Let's begin.
1. First of all You must have userbars (if You don't have, You can make them here
link)
I made two:
- userbar 1
and
- userbar 2
2. Make new document (with exactly the same resolution as yours userbars - mine have 300px x 19px)
3. Paste your userbars to that document (name them like in image)

4. Make a copy of your top layer (userbar 2) and bring it to the backward

5. Chose Move Tool (V) and take your top 'userbar 2' under the canvas

6. Open ImageReady (or just Animation window in CS3 version)
7. You will see the first frame. Press the 'Duplicates selected frames' button to make a copy of first frame

8. Bring up your hided userbar 2 (in 5. point) using move tool
9. Press the 'Tweens...' button and type '10' in 'Frames to Add'

10. Go to your last frame and take your middle userbar (userbar 1) under the canvas. Make top layer invisible
11. Duplicate last frame and bring up your middle userbar.
12. Press 'Tweens...' button and type '10' in 'Frames to Add'
13. We almost over. Now change the delay time in your 12th and 23rd frame to 2 seconds

And that's all
I hope that you understand all of it. If you got any questions just ask 
Good luck!