The spynet community--the community of folks providing feedback on the
actions they take with the product, the threats they see in the real world,
and what they get cleaned--is a major strength of this product.
Stats that I've seen published indicate that about half of the installs of
Microsoft antispyware opt into reporting. I wish that were higher.
The other important step you can take is when you find an infection--do a
Tools, Suspected Spyware report. If it is something new, or Microsoft
Antispyware can't clean it--that step will raise its priority in terms of
getting it into the definitions and able to be cleaned more quickly.