TALYA  I am disappointed that there's no support for the P1i!  
(Version 2.22)

W880NEWBIE  Wow, I just got my w880 and downloaded this software to customize my phone a bit, talk about making themes fast and fun.

It's super easy, has many many features, is free and you can customize your phone with it so 5 stars for what my value for it is, never crashed on me so gets a 5 star for stability too... A 5 star app.  
(Version 2.18)

AMAZING-EFFECT  These guys have a feedback section, so you can check it up with them and see what they tell you: http://www.myforum.lasyk.net/showthread.php?t=29423&page=14

The software did run right away on my MacBook (it ain't the Pro), and I am running 10.4.8, how did you get 10.4.9? It wasn't released yet!  
(Version 2.08)

AMAZING-EFFECT  Wow this is the best theme creation software so far for SE phones! I have tried the SE Themes Creator and boy does it suck, it was so sluggish I could just go out do my work, come back an hour later and it would still be loading! No offense to SE, but their software really made me want to cry at times! Thanks for this app... A MacBook user!  
(Version 2.08)

MEATMCGUFFIN  I can't get this to run, despite updating Java. I'm running a first gen MacBook Pro with 10.4.9.

Any ideas anyone?  
(Version 2.08)

JOOLS912  A very good, solid competitor to the official Sony Ericsson themes creator. It's certainly 100 times faster at showing previews of the themes, on my Mac.

To run it, you'll need to download and install J2SE v1.5 if you haven't already:

PPC Macs: http://www.apple.com/support/downloads/j2se50release4ppc.html

Intel Macs: http://www.apple.com/support/downloads/j2se50release4intel.html  
(Version 2.07)