Wellcome, if you want to leave a message, please do it in my Portuguese discussion page and If you do not speak Portuguese... at least try. We try :) This experience was illuminating and helped me a lot to understand the controversy, the lobby and the motivations behind the different Wiki projects. "another brick on the wall" i would say ...
If you do this, Wikipedia will show all times in Recent changes, page histories, and contribution histories based on your local time zone. However, when you sign a talk page with ~~~~, the timestamp is created in text, so it has to be displayed in UTC. Automated logs such as image file uploads are also shown in server time (UTC).
To show other users what time zone you are in, you could even add a time userbox to your own user page.