Here are 2 links provided by a ReneePearson.com student-sleuth who found a way for people to still get their trial software versions from Adobe. Here's the Adobe forum link, where people are discussing the issue, and where she found the link to this blog that describes the detailed process for getting the trial download.
I could hardly believe it myself when I realized that with the announcement of CS5 last week, Adobe removed all previous trial versions of their software from their site. The new CS5 trial (and software for purchase) won't be available until May - some support people I spoke with said May 1, on the website, it said mid-may - it's very confusing. So effectively this means there is no software whatsoever available for purchase or trial download at all from Adobe - and I confirmed this in several phone calls and a support email.
Thankfully it looks like there's a workaround available in the links above! Class starts tomorrow, and I would love you to join us if you haven't already signed up at ReneePearson.com. See the previous post below for more information about the class - and one thing I didn't mention before, you will have access to the training videos forever on the site, so you can always review everything, including all the downloads, after the class completes.