SPOILER WARNING

I was thinking the exact same thing, DC. Wikipedia has Curtis as being deceased...but I haven't found anything confirming on 24's official site. The fact that no one confirmed the kill, and the way Curtis collapsed...I think it can definitely be left open to interpretation. Take last season for example, when Secretary Heller drove his car off a cliff into the water below. Everyone assumed he had died...but we find out later that he survived.

You never know with this show! That's what I love about it.

***EDIT***

Wikipedia has now changed Curtis' status from "Deceased" to "Active"...so it's probably not safe to assume that he's either alive or dead. Hopefully the official website will have the answer up by tomorrow.