This is NOT true.  You keep the kit you have and use the AUX input instead of the FM transmitter for better quality, but you would have that extra receiver to worry about...  Dunno about you but I hate that extra unit, especially when parking a nice vehicle in a bad area.  If you do want to go that route, the new Sirius Sportster 5 model has the color changing button feature that will change all the LEDs in the unit to match the orangy glow that the Scion instruments have (as well as other colors).

There is a sirius reciever/antenna kit that will work with the factory radio (any of the three) but you MUST purchase it from Scion.  Best Buy does not carry a tuner that has the proper connection to work with the factory Scion stereo, despite their vast variety of sirius and xm tuners for satellite-ready radios - including alpine and pioneer (I asked the same thing because I didn't want to pay the $400 from Scion).  Good news if you have the time and patience to install it yourself, you can find the factory sirius tuner that installs hidden and works with your Scion stereo on eBay from Toyota Mall for $249.50.

http://cgi.ebay.com/ebaymotors/SCION-2008-XB-SIRIUS-SATELLITE-RADIO_W0QQcmdZViewItemQQcategoryZ38645QQihZ014QQitemZ330199228102QQrdZ1QQsspagenameZWDVW

Well, I mounted the radio in both cars yesterday & I think I like the way everything came out. I still need to hide all the wires in the xB, so I'll take pics once I'm done. For the xB install, I used the suction cup arm, but removed the suction cup and screwed it in down below the shifter, in front of the cup holders, so the SIRIUS unit is down low and doesn't affect night vision. Plus, it makes hiding the wires easier and you can't see the arm holding it up.

In the Camry, it was a little more tricky. I took out the center console, removed the cubby in front of the arm rest and screwed in the arm w/out the suction cup. It held horizontally over the edge of that cubby, before the shifter and cup holders. We can still use quite a bit of that cubby and nothing else is lost. It can also be flipped back toward the arm rest to hide it a little better. The wires are run under the console & up into the front cubby w/ the door. I still need to cut some grooves for the wires because, as of right now, the door won't stay closed. It may seem like it's not a great place because you have to look down to see it, but where it is, you can rest your arm on the arm rest and use the presets w/ your fingers w/out moving your arm.

Here are some crappy cell phone pics of the Camry - I think my wife left our camera at work over the weekend...  I hope it's still there!