Few days before, I wrote a tutorial on how you can build a web 2.0 logo with Adobe Photoshop. Here is another one for adding the reflection effect in a logo (like mine above) using Illustrator, which makes the reflection more flexible and easy to scale and manage. Open your logo in Adobe Illustrator and follow these steps:

1. Duplicate your image by pressing alt (command for Mac) and clicking it. Drag it down (pressing the “shift” key while dragging helps for keeping your image aligned) so it looks like the one below.

   

2. Select the original object and click object>lock>selection to lock it.
3. Select the duplicated object and click object>transfrom>reflect. Choose horizontal with 0 angle. Move the duplicated logo exaclty below the original one.
4. Select the rectangle tool and draw a rectagle that covers the reflected image like in the screenshot below (color does not matter).

   

5. Fill the rectagle with a white-to-black gradient, set angle to -90 and point color points like in the screenshot.

   

6. Select the gradient rectangle and the reflected image by pressing control+A (command+A for Mac) as the original object is locked and apply a transparency mask by clicking on the arrow in the upper right of the Transparency tab.

   

   

7. Drop down the transparency opacity to 40-50% to make the effect more realistic and your reflection is ready!

   

Note that making the reflection with Adobe Illustrator has nothing to do with the background color (like in Photoshop). Follow the same steps for applying it on dark backgrounds.