I fit into the 'older' category of IT worker and am finding no troubles with age discrimination. Its actually quite the opposite. We are finding it hard to find good junior techs with the motivation and focus required to succeed. This has led to guys my age being in more demand than ever. So I cant complain!!

Also, the most valuable guys I have worked with are all 40+.
Experience, plus coming from a time when hard work was normal means these guys take long hours and complex problems in their stride. Just hope I can be at that level when I'm mid 40s!