The new release of the SILC Plugin fixes several minor bugs and inconveniences discovered since the last release.
Besides this, the whole build process has been replaced by a new one. There is no automake/autoconf ruleset anymore which will guide you through the process of compiling the plugin but a detailed description of what you have to do.
This has two reasons, first of all, this versions adds a perl module Irssi::Silc which required large changes to the build process anyway. The other reason is that the old method didn't work on NetBSD or Solaris systems. This limitation is now overcome. I may eventually automate the build process again, but actually, I'm quite happy with the way it's done now.