Well, the United States and Iran are apparently going to set aside their differences (for at least a little while) so they can talk about Iraq. Surprisingly, we will NOT be talking about the various other issues at play here, such as the Iranian nuclear program or Iran's support for Hezbollah.
Also important: The talks are only going to be at ambassador at level, which means that this, while important in the sense that it is opening up the door, is unlikely to mean large, sweeping changes in Iraq anytime soon. (Not to mention the other problems Iran is causing in the area!)
This comes after some low-level Iranian and US officials "ran into each other" in Egypt a while ago (when people were wondering if Secretary Rice would have a similar "run-in" with her Iranian counterpart).
Personally, I think the strategic situation in the Middle East has changed somewhat, and that these talks can be a good idea. Hezbollah got worse than it gave in the recent battle, and is probably still licking its wounds, even if Hamas is crazy enough to renew rocket attacks against Israel. The attempt to overthrow the Lebanese government similarly failed, the Saudis are procuring more advanced weapons, and many Gulf States have gone to the IAEA to register their own nuclear programs.
In addition, Ahmadinejad is having big problems at home. Oil prices were lower than anticipated and a quiet US Treasury campaign has denied Iran supplies of hard currency. The end result? Iran is cash-strapped, both nationally and internationally. The economy is bad enough that recent elections turned against Ahmadinejad, and the Russians are quite annoyed that Iran has not made recent payments on its reactors.
The broad picture has gone against Iran, which was expecting aggressive confrontation; rather, they got an indirect assault and a proxy war, and is currently getting hit hard. The broader picture still is in Iran's favor, as they will get nuclear weapons within the next few years at the present rate, but the situatuon is much less bleak than it was, and therefore we don't have that much to lose by restricting the topic to Iraq.
On the contrary, we have everything to gain. By making concessions only within Iraq (which is ugly anyways) we can keep our hand steady outside of it.
I'll be watching. I'm expecting a few overtures and gestures, but, in the end, nothing will occur. By the end of the year, though, I expect more serious talks between the US and Iran.