Zip and Tuple Neatness

In BCL 4.0, there’s still no Unfold method (boooo), but at least there’s a Zip extension method to keep us warm as winter draws on.

I played with it thusly:

Chain – a LINQ operator for dealing with Linked Lists

I don’t think there’s anything in LINQ that will do this, though I expect I’m wrong – I have a tendency to write my own extension method to do something and then discover that LINQ already provides a general version of it. But in the mean time, here’s my Chain method:

Observable Property Pattern

Is there something like this in the standard libraries? And if not, why not?