Yes, it's not that TRIM and RAID causes a problem, it's that Windows 7 won't recognize discs in a RAID array as SSDs and therefore won't use TRIM at all.
It appears that if a RAID controller reports it's virtual RAID volume as being "0 RPM", then windows will treat it as an SSD and issue TRIM commands. But that requires specific support in the RAID controller - not only to report the correct information but also to accept the TRIM commands and translate them as necessary before passing them to the SSDs. (For example, if Windows issues a TRIM command that says Disk Sector 100 is now empty, the RAID controller has to decide which drive to pass it to and it also needs to translate the 100 into the appropriate sector for that drive).
Since TRIM is a very new addition to the SATA command set, it's not really known right now which RAID controllers (if any) can do this and which can't.