x11-terms/st has changed license to MIT/X according to their website: http://st.suckless.org/ (in Download section) and this commit: http://git.suckless.org/st/commit/?id=9df1e56142527de1b8917434093d25212dd9da1e This change happened between 0.3 and 0.4, so all versions currently in Portage tree (0.4, 0.4.1, 9999) are under MIT license.
Looks like LICENSE="MIT-with-advertising" to me.
+ 17 Jun 2013; Michael Weber <xmw@gentoo.org> st-0.4.1.ebuild, st-0.4.ebuild, + st-9999.ebuild: + Update LICENSE to MIT-with-advertising (bug 472664, thanks Jack Chen) +