Sure. PowerPoint has a "Save as Web Page" option.
Try it once. You'll be amazed at what Microsoft considers to be HTML markup. Watch out for scads of little graphic files for each page if you did any line-drawing graphics with PowerPoint tools.
You'll never try it again.
The only viable option for graphics-heavy presentations is to do a screen capture of each PPT page, and use that as your HTML page. For text-based presentations, cut and paste the text from PPT to an HTML editor, and rebuild the page.
Or you could simply post the PPT files and have people download them as-is.
I'll bet you were looking for Good News.....
(ben says): Please don't make screen caps of each slide... all you have to do is go File | Save As... and choose TIFF. TIFF is the only way to get good quality slides out of the presentation. Then use Fireworks or PS or something to batch convert your TIFFS into GIF's at whatever resolution you need.