MACUPDATE ADMIN  From the developer's site:

"Why no Intel version?...

Until a couple of weeks ago, the primary reason would be no Intel machine available for testing. Recently though, I was finally able to purchase my first Intel-based Mac (actually my first Mac purchase since my G3 Powerbook in 2000). I've now received that MacBook Pro and assessing the possibility of reworking TransparentDock to allow customization of the Dock on the Intel-based Macs. What I've found so far is that the current patches that were established for Dock customization by TransparentDock on PowerPC-based Macs will not work for the Dock on the Intel Macs. So it seems it will take some time to determine what's possible, and whether perhaps an entirely different approach may be necessary. So, I guess the short(ish) answer now would be I haven't yet established access to many of the TransparentDock options for the Dock running on Intel Macs. So... why do other application(s) continue to work on both PowerPC & Intel Macs that modify the dock appearance? Mainly due to a different patching approach, for which I have only found success with modifying the dock window attributes (color, transparency, etc.). Many of the other dock customizations available within TransparentDock have proven more difficult to access using current patching methods."  
(Version 2.3.9)