I just pushed the changes associated with PSARC 2005/425, which is basically the removal of the script wrappers /usr/ucb/cc, /usr/ucb/lint, and /usr/ucb/ld. The fix will be in b122 of ON.
This is a good thing for people who build free software bits on OpenSolaris. For a long time, there have been complaints that /usr/ucb on your PATH was particularly toxic (some would say it was toxic anyway, but that's a different matter) -- autoconf scripts were frequently confounded by /usr/ucb/cc, which has done nothing more than generate a useless error message for most people.
So, /usr/ucb/ on your path, while not recommended, is at least no longer particularly toxic.