I noticed that net-im/kopete and kde-base/kopete doesn't depend on media-gfx/imagemagick. But it needs it when the user enables the latex plugin. Without it will display a error box that convert wasn't found. net-im/kopete only needs to depend on imagemagick when the latex plugin is enabled.
I won't add it for kde-base/kopete (at least not for <3.5.5) as that would require it to be always merged, and it's not a good idea. I'll add it to runtime dependencies for net-im/kopete though.
Thanks for reporting, added now.