We check this website, now craigslist.com.sg is up and dont blocked for our system and other users of the Internet.
So, answer to question: Is craigslist Down Right Now? - NO! craigslist is up!
If you have problem with access to site craigslist, and domain craigslist.com.sg is not avalible.
Clear browser cache and/or try other web browser
(Chrome, Firefox or Safari).