The steam version currently works.
If you install steam from the CrossTie engine, you only require .Net 2.0 to be installed.
Steam installs all other needed Microsoft Redistributables for you.
The launcher has some quirks, but functions, and the game runs near flawlessly except for some lag in texture loading that results in objects appearing all white when you first enter an area that has been viewed for a while, and a handful of particularly blurry textures at distance on low quality.
Online features do work as well.
There are minor graphical glitches in the background when at the starting menu, and minor sound glitches at this point. They don't interfere with the menu, and the sound works fine in-game. Some users have reported issues with textures. I have not personally experienced this issue.
The game changes the Gamma on your display. Normally it will change it back on exit. If you change virtual terminals under Linux, and switch back, the display will appear too dark. Also, if the game crashes, you may need to reset your Gamma or restart your X-Server as well as change your video mode back.
Falsely reported "Please Register Your Game" on previous versions of Sims 3 and/or Crossover. Newest version of Crossover and/or the latest patch set to Sims 3 Executable seems to fix this.
To repeat the instructions clearly:
Install Steam from Crossties *(You can use your regular Steam bottle, if you have one.)
Install .Net 2.0 to the Steam bottle using Crossties
Install Sims 3 from Steam
(Post Updated 11/11/2012)