TRIM is a Windows 7 feature. It is simply a message from Windows 7 to an ssd that tells the ssd a pc user has deleted files. An ssd may or may not be able to use the message to enhance its own "garbage collection" process. For example, multiple ssd's in a RAID array do not support the TRIM feature. That is about to change because a process has been developed to allow ssd's in a RAID array to support TRIM.
The ssd "garbage collection" process has also changed. The process has become more aggressive because there are additional situations in which the Windows 7 TRIM feature is not supported. Garbage collection has been improved and ssd's do fairly well without TRIM but there is still room for more improvement.
I personally do not know of any PCI-e based ssd that supports the Windows 7 TRIM feature. The PCI-e based ssd's have multiple controllers in a RAID array. The biggest problem is cost.
The situation "might" change sometime between October 1st and the end of this year when Intel and other companies introduce their own PCI-e based ssd's. There isn't much information available right now.