Ruby block syntax is straight up lifted from Smalltalk, not to mention much of the semantics and standard library. Ruby seems like what Smalltalk would be if it was built as a scripting language with file-based structure... and then dragged through the mud of Perl syntax. ;-)
At first glance, the two languages seem similar, but not as much as Clojure is to CL (or any other lisp).
In particular, Clojure's preference for vectors over lists in many situations, combined with its much stronger preference for immutable objects makes it highly distinct from CL.
The requirement for explicit trampolines to allow efficient tail-calls makes it distinct from any (non-toy) lisp I've ever used.
Uh... no it's not, it's lifted from C/Perl with a smattering of Pascal.
> not to mention much of the semantics and standard library.
The semantics are as much Perl as they are Smalltalk, if not more so. And many pieces of Smalltalk are missing (first-class blocks to start with, Ruby's blocks are a hack)