I suspect the "GCC" intervention in Bahrain — which apparently consists of about 1000 Saudi forcesa — while a direct response to the worsening of the situation yesterday, also is taking advantage of the fact that, in the wake of the Japanese earthquake/tsunami/nuclear disasters, the world's media attention is focused elsewhere. While most major news networks deployed heavily to the Mideast in the past few months, the big names have moved on to Japan, while those remaining in the Mideast have to also cover both sides in the Libyan war. Yemeni forces have been using greater force with the protesters as well, in part because the whole world is now occupied elsewhere.
A more disturbing thought is that the world's distraction may not be the only reason governments are cracking down harder on the protests: despite the Arab League's unprecedented support for a No-Fly Zone in Libya, beleaguered autocrats may be emulating Qadhafi on the assumption that a hard line still works. I'm not sure that it does in the long run, but it may in the short run.
The US response is going to be interesting. A lot of Bahraini opposition figures have already noted that US Defense Secretary Gates was just there on Saturday. I don't believe it's cause and effect, but many in the region may well jump to that conclusion.