Not.
Chinese internet users aren't stupid, they know what is going on. In many cases, all it does is call attention to the anniversary, perhaps more than would have been paid otherwise.
In any case, most Chinese I know seem fairly cynical about it. A translated conversation from Xiaonei, in response to a blog post by a friend about the economic crisis:
AAA: Well written!! But why can't I share it? (think Facebook sharing, posting a link to it on your own homepage)
BBB: Yeah, I can't share it either. Must be because it's today!
000(the author): Well, I can post it, you guys should be able to share it....
CCC: (a few comments about the actual content of the article)
DDD: I guess Xiaonei is having problems recently. Anything with numbers seems to run into problems.
AAA: Anything with certain numbers runs into problems around this time of year....
EEE: I'm sure this maintenance is perfectly normal, as it is for all other Chinese websites right now.(sarcasm)
BBB: There is no spoon~~! (this in English)
FFF: Wow, nice word choice guys.
Bad translation, there was a good pun or two in there I couldn't figure out how to translate. In any case, they're masters at not using any words censors would find suspicious. But they're all at least aware of it, even if its a minor annoyance.
And it will probably remain just that: A minor annoyance for most, perhaps making them remember, but they don't care that much. The ones that really want to protest will just use text messages or IM anyway, and even they hardcore democracy types know where the line is drawn. For the most part, it seems really unnecessary. If they really wanted to organize protests, they'd have been organized long before the 3 days before the anniversary, and then use texting or cells or IM to expand. I doubt there will be any protests to speak of anyway- the Chinese sort of have a silent agreement here, they know where to draw the line.