The current scilab roadmap at www.scilab.org shows that version 5 is to
be coded primarily in java. Not due for about a year though - nothing
available to download yet that I can see.
Java is looking like possibly a good choice for open source math
software, with Sun moving toward gpl2 licensing for it. The scilab
license will be less free than the java it is coded in! I hope that
may change in the future.
I don't know whether underlying fortran libraries like lapack or atlas can be
linked with it.