So there are a couple of "closed" drivers that are not part of OpenSolaris, and might never be because of redistribution restrictions. However, this represents an opportunity for an enterprising software engineer to contribute. The drivers are
glm - Symbios 53x810 and similiar devices
qus - QLogic ISP 10160 and similar devices
adp - Adaptec AIC 7870P and similar devices
cadp - Adaptec AIC 7896 and similar devices
There are open source drivers for these from FreeBSD and NetBSD, which could be used as a starting point for a port. I'd probably be interested in trying one of these out myself, if time allowed -- but alas it does not, my plate is already quite full.
The best part of these drivers is that there are few, if any, "political" or "business" restrictions on integrating replacement drivers. Indeed, at one point recently each of these was considered for an EOF simply because they weren't considered strategic anymore. (The EOFs were rejected, but these will only be delivered via an extras repository or somesuch.)
So, what are you waiting for? This is a good opportunity to learn about SCSA, and provide us with superior replacement drivers. (The glm replacement looks like it could be done in as few as 2 or 3 KLOC; that is all the NetBSD version of the driver uses.)