I use it in Tiger, and Entourage and it works just fine.

BUT YOU HAVE TO KNOW WHAT YOURE DOING WHEN INSTALLING,

because SILK is a haxie, it messes with certain parts of the OS that Apple would not be happy about-which is OK as long as you know what youre doing;
MAKE SURE YOU HAVE THE LATEST VERSION OF APE-APPLICATION ENHANCER- thought SILK usually installs that for you..

1. Quit ALL apps-and ya might as well unplug everything except KB&M, just to be safe.

2. do a restart, holding down 'command-S' at the same time;
When the prompt appears #Root: (or whatever) type: FSCK -FY (hit return) IF it comes back with "FIXED, but FILE SYSTEM WAS MODIFIED, keep doing FSCK until it doesnt say that anymore.
at the end of a final FSCK, reboot, holding down the shift key.
You will enter single user SAFE BOOT mode; log in.

3. Go to Disk Utility and repair permissions..

4. THEN install Silk, and configure it to your liking;
Reboot, repeating step 2-FSCK but dont hold down the shift key after rebooting-go back to normal mode; Repair permissions again.
I can guarantee you will have no problems with Silk on Tiger if you follow this simple proceedure;

I HATE the rather boring Apple default font Lucida Grande-I use Papyrus-I also customize my folders from the rather drab shiny blue ones the Apple defaults to;
I have one spiffy looking desktop and system.
Remember, Silk CAN cause you system problems if you dont install it correctly.