There were numerous updates, here are only the more 
important things.

Version 1.99 
- New fast directory view ! This part is now totally rewritten; 
  no more lost files and uncomplete lists. Files are shown in the 
  order how they stay in FAT, that means unsorted. Comming in next release: 
  sorting files in alphabetical order. 
- Fixed bugs with some ICOs, and compressed BMPs 
- "Read ahead" - processing next image in the background is not implemented. 
  It doesn't bring wished effects, especially on faster machines (pentiums).
  Why?
  Besause the background processing of the next image slows down showing 
  of the previous (even on faster computers, even with faster graphic cards). 

Version 1.98a
- Fixed bug with 256-colour-ICO
- Fixed bugs with fit-to-desktop and resize
- New menu outfit
- Zoom percentage shown in title bar
- Positioning window somewhere else than top left 
  corner
  (biggest known bug: IrfanView still can NOT correctly
   resize images whose dimensions exceed actual screen 
   resolution; if you do not want to cut edges of your 
   image, void saving in this situation)

Version 1.98
- Viewing ICO 
- Zooming in and out 
   in: 150, 200, 250, 300, 500, 600, 700, 800, 
   900, 1000 %
   out: 90, 80, 70, 60, 50, 40, 30, 20, 10, 5 %
   (known bug: zooming in large images works till
    now only up to 500 %)
- Resize image

Version 1.97
- Viewing RAS
- Fixed some bugs with fast directory view and GIF

Version 1.95
- Viewing TGA
- Image flip/rotate
- Image copy/move to another directory
- New tab-dialogs (Menu: Options->Properties)
- IrfanView32 doesn't support Win32s any more

Version 1.90
- Viewing Photo CD
- "Fast directory view" (jump to next image in the
  current directory with space, to previous with
  backspace)
- Set image as wallpaper

Version 1.85
- Windows 95-dialogs (open/save file)
- Viewing 2 bits per pixel PNG
- Saving file as TIFF

Version 1.80
- Viewing PCX and RLE
- Viewing grayscale TIFF
- Fixed some bugs with GIF

Version 1.70
- Viewing TIFFs (uncompressed, LZW, packbits, Huffmann
  fax group 3, fax group 4)