This bug is in the 2.2.x series If you execute a TRUNCATE ONLY sometable; The log trigger on 8.4+ systems will pass the truncate and perform the truncate on replicas. However the apply function is doing TRUNCATE someschema.sometable which ignores the 'ONLY' causing any child tables to also get truncated.
Created attachment 208 [details] truncate only on replicas
Fixed in 2.2 stable http://git.postgresql.org/gitweb/?p=slony1-engine.git;a=commit;h=d49be55403545271751c44bc3f9266689b9a5ba4