I looked around for a fix, but I didn't find anything that adequately addressed the issue, in my opinion. A lot of people have figured out ways to force the NavBar to be transparent. This kind of works, but it doesn't fix the jagged edges and poor quality of the original image.
So I went to work on my own. I first noticed that the lock screen has a PERFECT NavBar image. THAT'S how it should look on the home screen. After a bit of hacking and learning how Sense 3.0 themes work, I figured out how to get that perfect lock screen image showing up on the home screen.
The fruit of my efforts so far is located at:
You can download and install the APK's directly, then load them using the built-in skin chooser. Keep in mind these are Sense 3.0 QHD only. If you don't have a QHD (960x540) Sense 3.0 device, like Sensation or Evo 3D, don't bother.
I've also included a /notes folder describing exactly how I fixed the issue. This is only for general curiosity. YOU DON'T NEED TO LOOK THERE TO BE ABLE TO INSTALL THE THEMES. It could, however, help someone fix the skins for lower resolution devices (like 800x480).
Finally, I made the status bar jet black, because that's the way I want it. If you don't like it that way, feel free to insert your own status bar image. It's in the APKs' res/drawable-hdpi folders as statusbar_background.png.
Here's how it looked before (as seen in the stock Blue Sky skin):
Here's how it looks in my fixed bluesky.apk:
Better, no? Now we don't have to wait for HTC to fix it. :)