I believe Apple stopped providing security updates for OS X Tiger last month. That, coupled with all the problems Mediacom (my ISP) has bestowed upon it’s customers, plus the failure of my iBook’s tracking pad have made my Internet experience rather painful for the last month or so...
I have to say that when it comes to long-term product support, Microsoft wipes the floor with Apple. That plus there’s no clear Apple lifecycle policy, while Microsoft has a clear policy for all operating systems.
Apple had better start doing that if they want to get more into the enterprise. An enterprise that buys software wants to know exactly how long it will be supported.
I don't believe that is the case. I can find no reports of OS X support discontinuation. Apple's policy is to support the OS for five years from the release date. That would put the discontinuation next November 2010. Apple has released a Security update for Safari 4 for OS X.4, OS X.5 and OS X.6 in November 2009 which would be consistent with their policies.
For your iBook... try plugging in a standard two button scroll mouse and using it until you can get your laptop repaired.