Scribble @ syntax appears to not function in the SBCL 2.1.1
Attempting to test in the SBCL repl gives the following results.
CL-USER> (named-readtables:in-readtable :scribble-both)
#<NAMED-READTABLE :SCRIBBLE-BOTH {102887B2A3}>
CL-USER> @print{test}
; Evaluation aborted on #<UNDEFINED-FUNCTION RINT {102A145163}>.
However, using instead @@print{test} appears to work. It seems that the first character is consumed prematurely somehow.