On January 1 the new California Consumer Protection Against Computer Spyware Act came into force.  Via Information Policy, the "Act makes it illegal
for anyone to install software on someone else’s computer and use it to
deceptively modify settings, including a user’s home page, default
search page, or bookmarks and outlaws the collection, through
intentionally deceptive means, of personal information through
keystroke-logging, tracking Web site visits, or extraction of PII from
a user’s hard drive."

Slashdot discussion and flame wars here.