Unfortunately, due to one of my previous employers thinking that buying production servers from eBay was a good idea, I have TONS of experience with this kind of error.
This is definately a memory error, on dimm J3300 on system board 7. If you notice, it reports CPUs seeing errors several places, but it is a different CPU each time. If the CPU was failing it would always be the same one. But each time it says the memory module the error came from is the same one, which tells you that is the root cause of the error.
Also note, at the top of your output the error was intermittent, but by the bottom the error message said it is persistent. This isn't a good sign . . . Solaris can accomodate occasional memory errors, but if it is the same dimm constantly doing it like that you'll panic your box eventually. I would either replace that memory, or at least remove that bank and run with less memory. Better to run short than crash your box.