According to the review site Anandtech.com, some units of the recently released MacBook Pro show support for the TRIM standard on solid-state drives.
A screen shot from System Profiler running on the 13-inch MacBook Pro shows the settings for a Patriot Inferno 100GB SSD. It lists TRIM SUPPORT after Medium Type and Partition Map Type settings. The article said this setting wasn't revealed on the new 15-inch and 17-inch machines.
The OS still incorrectly identifies SSDs with TRIM support as not supporting the instruction, but I get the feeling we're close to having TRIM support in OS X. At which point we'll be even closer to Apple shipping some halfway decent SSDs in their systems. It's taken this long but we're getting there.
The TRIM standard helps SSDs manage garbage data, which can help avoid the write performance slowdown that occur over time as the drive is used. Support for the standard is reportedly in Linux, BSD Unix, Windows 7 and Windows Server 2008.