Usually, if a state is trying to show friendliness, it stays friendly. If it is trying to throw its weight around, it does not pander. If it is trying to subvert its enemies quietly, it stays quiet. China may be trying to do all three, particularly to the US and the West, and in the meantime, is leaving the US State Department baffled.
1) Friendliness. Perhaps to make up for terrible PR due to its relationship with the Sudan government and oil industry, China is sending PLA troops on a peacekeeping mission in Darfur, though it's only a 315-man engineering unit sent for UN support. While little more than a token gesture, it shows that Beijing is willing to make such gestures for the sake of goodwill.
Furthermore, PLA counter-terror troops continue to do joint drills with regional neighbors; most recently, Russia. In addition to the joint training with many Central Asian states, China seems to be making waves about being a front-line anti-terror state, though it's largely using this as justification for suppression of Uyghurs in its northwestern Xinjiang province.
2) Throwing Around Weight. China continues to refuse multilateral negotiations over the Spratly islands in the South China Sea, insisting bilateral relations with each of the ASEAN states involved. China's military spending is increasing each year, and while the coming Olympics has kept Beijing quiet on the Taiwan issue, the PLA Navy still looms. Though Taiwan's KMT victory is likely to lead to an ease in China's Taiwan stance--they will have a government they can talk to.
3) Subversion. The Pentagon claimed a few months ago that Chinese network spy-hackers had broken into Department of Defense Mainframes. Pings from Chinese government-controlled computers are ubiquitous, but are probably mostly for mapping purposes. Chinese officials occasionally try to bribe American network security experts for privileged information.
Most recently, the FBI has gone after 4 Chinese nationals and one former State Department analyst for the transfer of American military secrets for money. No word yet if the American analyst will be charged for treason, but for the FBI to make a public move like this in (what seems like) a traditional spy vs. spy game, one should start thinking that the FBI either has rock-hard evidence or a critical and urgent case. It's something worth keeping an eye on.
Ultimately, the Chinese are keeping their poker hand close to their chest. Their leadership talks of a "peaceful rise" (which they say most modern powers had not been able to achieve in the past), but is fully prepared for any espionage or military matter it might have to face. What China wants-- should it be only the return of Taiwan, control of the South China Sea, containment of Japan, or East Asian hegemony-- is uncertain, leaving the US in an awkward hedge strategy: the US is engaging China and trying to pull it close economically (though not diplomatically) as it rises, in hopes that US and Chinese interests might converge, but on the other hand, is keeping Taiwan's military strong, and encouraging Japanese naval growth to keep China in check.
It's an awkward game from both sides. What is likely to clear things up a bit is a more open statement by the Beijing leadership on what China wants... but I'm not even sure that they really know.