Using AppFabric session state provider, does each session get its own region?

Question

I've been playing around with AppFabric Beta 2's session state provider. It appears that each new session get its own region (named "Default_Region_XXXX" (where XXXX is an apparent random sequence of numbers). If I understand regions correctly, it appears that each region is tied to a single cluster host, leaving a single point of failure. Why is each session being given it own region?

Also, do sessions eventually timeout and clean themselves up in the cache or is that behavior just inherited from the cache settings? I'm wondering (if in a production application scenario), if one would use a separate named cache for session state apart from other application caches?

Thanks.