Google Presentations looks good, simple and easy to use. The biggest limitation is that you cannot export the online presentation to PowerPoint (yet). Google cleverly circumvented this by exporting to zip/HTML which allows the presentation to be run locally on any computer without the need to install PowerPoint or similar programs.
See a sample new presentation here along with my old presentation on Web 2.0 in Medicine from 2006 (uploaded PowerPoint file).
I have linked to several in-dept reviews in the reference section below but Geeking with Greg provides the best summary:
"Stepping back and looking at the bigger picture here, I find myself getting to the point where my entire day is spent in the browser. Even on machines where I have Microsoft Office installed, I often find it faster to quickly view documents using the GMail integration with Google Docs than open other applications.
I was skeptical that Google would get us to that point, but they have. Google appears to be making remarkable progress chipping away at the utility of a desktop PC environment."
Google Docs in Plain English
Google Presentations Finally Launched. Google Operating System.
Google Presentations Released. Philipp Lenssen.
Say Hello to Google Presentations. PStam.com.
Google Presentations a quick review. Google Tutor.
Google launches presentations, but shouldn’t have. Googling Google.
How To Embed Google Presentations. InsideGoogle.
Our feature presentation. Google Blog.
Google's PowerPoint launches. Geeking with Greg.
Matt Cutts: Gadgets, Google, and SEO. Matt Cutts.
Image source: Google Operating System, a Creative Commons Attribution license.
Google Docs & Spreadsheets Could Replace Word & Excel for the Average User
Adobe joins rest of industry in going for Microsoft’s throat. Scobleizer.com, 09/2007.