No you totally want marketing to be talking about something in the same place, even if they are wrong. It would absolutely not suck if they posted something incorrect, because then the people that know better can post alternative answers and/or comment and help correct the information.
If you put them in separate stacks, the bad information will just persist and live in isolation, and never get corrected.
You basically want to do everything you can to prevent silo'ing of people as well as knowledge. You want people talking.
Consider too that not everything posted has to be about technology. It can be recommendations for a good restaurant near a customer site, or where office supplies can be found in a large, multi-site office, or how to request facilities to come fix a leaking faucet.
