The Google dev team is dropping .NET 1.1 support in the near future [from the] Google Data APIs .NET Client Library:

For a lot of reasons, mainly additional work involved maintaining and
testing under .NET 1.1, and the missing language features (every time
i need to write another collection....) i am planning to move the base
line of the code to .NET 2.0.

This implies:

-> no more .NET 1.1 solution files
-> instead .NET 2.0 solution files (VS 2005 compatible)
-> language features will be used that will no longer compile
in .NET 1.1 (that is a gradual change).

Normally when I see open source/use libraries making decisions like this, I think it's a sign of misplaced resources, but here... well, you tell me how many people are going to be affected by the change and what it tells us about .NET adoption rates.