Probably not as big a deal as some of the blogs are making it sound (some make it sound pretty serious), but have a copy of your passport and work permit in your pocket at all times anyway. Better to be safe than sorry.
Here's a copy of the forwarded message thats been going around. You can also check out this post by cityweekend on the subject. Theres not much information on what is exactly going on but I'd expect it'll be harder for those expats working on travel visas to make their HK runs. I expect that those who are working should be sure they have all their information memorized and on them and of course are working at legitimate companies and not working illegally.
Thank you dumbass brit in beijing, dumbass english teachers who are disrespectful, dumbass forgeigners who don't understand the culture and are rude, dumbass everyone for bringing this down. I think eventually this will happen anywhere the local population and foreign population don't mix often or well. Lets make a better effort from now on, me included. Not blaming the foreigners only for this, its wrong to scare people legally in the country and stirring up animosity if thats what this program is designed to do, but i don't think thats the case. I think they're responding to local resentment of the actions of a few dumb foreigners and since there isn't a lot of mingling, some locals can get the wrong impression about the expat community as a whole and call on this stuff.
Just rambling now but now thinking of it though, the CCTV anchor that started the whole "Foreign Trash" talk on his blog should know better and he's talking smack too, so who knows what's the cause.
As the email says though: keep safe, tell everyone.
---------- Forwarded message ----------
Not sure if some of you already know, but 50+ policemen surrounded the apartment and yongfu lu yesterday around 11pm to check all of the foreigners that were there.
they have a little machine were they input your passport number and if the light goes green, then you're good. if it goes red....then they take you away.
just make sure you've got a copy of your papers on you all the time. a photocopy, pic on your iphone, whatever.
as said in dans's email, this is a 100 day campaign started by the chinese central government in beijing, so it will last until the end of august.
PLEASE BE CAREFUL.
and tell everyone.