Determining pdf vs. dvi output at runtime

I have a document using this macro to control various actions depending on whether it was
being built under regular (pre-3.0) latex, or pdflatex:

\newif\ifpdf
\ifx\pdfoutput\undefined
   \pdffalse % we are not running PDFLaTeX
\else
   \pdfoutput=1 % we are running PDFLaTeX
   \pdftrue
\fi

I gather that in 3.0, \pdfoutput will be defined even when running 'latex' - is
this correct? If so, is its value 0 when invoked as 'latex', so I still have
some way to determine what this macro wants to know?

Thanks,

Jon