A big problem with Guido's considering type declarations for Python is that there are now at least three significant implementations of Python. Disregarding how you or I feel about this specific proposal, any big change in the language will put further distance between the implementations or impose a heavy fine on those implementations that are trying to keep pace.
Given the momentum in favor of Python over the last year, if I were the BDFL of Python, I would freeze the language at the 2.4 specification for a few years. This would allow the other implementations to catch up, and allow the CPython implementation to focus under the hood on implementation improvements.
I'd have to see real evidence of pain and suffering to want to extend the language significantly. Let other languages try new ideas, but Python should probably stay close to the current definition which has brought it to the threshold of something big.
Of course Guido's current thoughts just exist on his blog as far as I know. Real changes to the language based on these are a long way off. They could have an ill effect on the current momentum just the same. At the least they could suck energy away from more immediate concerns.
Comments are enabled for the concept of a moratorium. No type checking debates here please.