From Mac Guides
iPhoto 1.0 was introduced at Macworld San Francisco in January 2002.
New features included performance enhancements, a new folder structure for photos, CD burning, slideshows, the Organize tab, and the Retouch and Enhance tools.
iPhoto 4.0 was released at Macworld San Francisco in January 2004, as part of the iLife '04 package. The version number was no doubt changed to 4, not 3, to match the package title, which in turn matched the year of release.
iPhoto 4 claimed to support 25,000 image libraries with little decrease in speed, something that was a problem with older iPhoto versions. iPhoto 4 also introduced the ability to share photos and copy them across your network, much like iTunes but without the DRM, as well as performance enhancements, smart albums, photo rating, rendezvous photo sharing, and improved slideshows.
iPhoto 5.0 was released at Macworld San Francisco in January 2005, as part of the iLife '05 package.
New features included soft cover books, multiple book sizes, importing of video, and an iTunes-like search field.
iPhoto 6.0 was released at Macworld San Francisco in January 2006, as part of the iLife '06 package.
New features included new cards, calendars and books, photocasting (podcasting for photos), one-click effects such as sepia and B&W, and an increase in maximum library size from 25,000 to 250,000.
iPhoto 7.0 was released as part of iLife '08 in August 2007. New features included events, new editing tools, new calendars and books, a unified search, .Mac web gallery and theme-based home printing.