For OS X, I don't know about defrag at all, but I do know that Apple has been late to add TRIM support. Right now (as of 10.10.4) I believe you still have to run a shell command to enable it, or did as of January this year, and more complete support is expected with El Capitan.
Windows 7 (and later) had TRIM supported added via Windows Update back in 2010, but it was disabled by default in most cases (the bios must be using AHCI mode, which was less common then). There have been updates since both from Windows and OEM manufacturers that make it much more likely to be enabled today. Generally, Windows does the right thing here. Additionally, Windows is smart enough to know the difference between an SSD and an HDD and won't try to background-defrag SSDs very much (see here: http://www.hanselman.com/blog/...)
I don't know of any **mature** file system designs that are explicitly optimized for SSDs from day 1, but I'll be surprised if one isn't in development.
FORTUNE'S FUN FACTS TO KNOW AND TELL: #44 Zebras are colored with dark stripes on a light background.