According to several open bug reports, the current stable sbcl (1.0.55-r1) fails to compile. There are currently no open bug reports on 1.1.11, although there are some on 1.1.[6-9] that should be verified.
+ 10 Dec 2013; Chema Alonso <email@example.com> sbcl-1.1.12.ebuild:
+ Stable for amd64 wrt bug #485630
Stabilization revoked, bug #485632
+ 12 Dec 2013; Chema Alonso <firstname.lastname@example.org> sbcl-1.1.12.ebuild:
+ Revoke stable for amd64 wrt bug #485632
*** This bug has been marked as a duplicate of bug 511170 ***