Syria's recent warming up to the West--including joining the Mediterranean Union, working on serious peace talks with Israel, establishing diplomatic ties with Lebanon and agreeing to demarcated borders, and visiting Europe to talk about security problems in the Middle East--has started to show evidence of serious consequences.
The most recent is a bombing in Damascus that killed 17--a very rare event in Syria, which keeps control with ubiquitous security and sometimes-brutal repression.
But Syria doesn't have control over the entire desert to the east of Damascus, where a large number of Sunni extremists sit around steaming about Syria's relationship with Shiite Iran. But these Sunni extremists also happen to really like the Sunni extremists in the north of Lebanon that benefited from Syrian control, and both groups are now upset that the Syrians are supporting the elected Lebanese government.
But this comes with a drift away from Iran and a lowering of support for Shiite Hezbollah. Normally, I would suspect the Sunni extremists to write such a policy off as a bit of a wash, realizing that the Syrians are breaking with the Shiites much more than anyone else. The Sunni militants' biggest beef is probably that the Syrians have tightened security in their Iraqi border, which would prevent such militants from pushing manpower and weapons into the fight.
But there are other culprits. Syria has a lot of powerful security forces that are intense rivals of each other, and may be locked in a power struggle. They were responsible for a number of coups during the Cold War, but there is some evidence that Assad's decision to liberalize may be causing one coalition of security groups to flare up and the other to try to protect the current government.
The best example of this kind of circumstantial evidence is the bombing of a prominent Hezbollah leader in Damascus back in February. While Hezbollah and Iran were quick to blame Israel (for which I'm sure the Mossad is quite flattered), it's unlikely Israeli security has the kind of operational freedom in Damascus to get away with such an assassination. The bomb was entirely possibly placed by a pro-Western faction of the Syrian security forces, possibly in hopes of causing strains in the Syria-Hezbollah relationship. This could be the work of anti-West security forces trying and failing to hit someone in specific.
The evidence for this bomb being the doing of Sunni militants is that in the last few weeks, Syria has put a bunch of troops along the Lebanese border--this looked like it was primed to go back on its promises to Lebanon earlier, but the Syrians had voiced no reason why they might. In retrospect, it looks like they were trying to prevent northern Sunni militants from flooding in and trying to conduct operations in Syria. Their success was possibly not complete.
Either way, this kind of bombing is likely to worry Syrian civilians, but probably won't cause them to take an appeasement route with respect to extremists and terrorists. Syria has the will and the capability to deal with these guys, and simply needs to execute another crackdown. If it can manage to control its borders with Iraq and Lebanon, then it can even try a systematic in-house cleaning operation--though getting rid of militants forever is unlikely to happen.