Exploiting the possibility for :fmt to be a function it can be done as follows:

\documentclass{article}
\usepackage{comment}
\begin{document}
\begin{comment}
  #+ORGTBL: SEND table-name orgtbl-to-latex :splice t :fmt (lambda (str) (format "%.2f" (string-to-number str)))
 | 1.000 | 2.000 |
\end{comment}
\begin{tabular}{lrr}
  % BEGIN RECEIVE ORGTBL table-name
  % END RECEIVE ORGTBL table-name
\end{tabular}
\end{document}

Exploiting the possibility for :fmt to be a function it can be done as follows:

\documentclass{article}
\usepackage{comment}
\begin{document}
\begin{comment}
  #+ORGTBL: SEND table-name orgtbl-to-latex :splice t :fmt (lambda (str) (format "%.2f" (string-to-number str)))
 | 1.000 | 2.000 |
\end{comment}
\begin{tabular}{lrr}
  % BEGIN RECEIVE ORGTBL table-name
  % END RECEIVE ORGTBL table-name
\end{tabular}
\end{document}

Note: :fmt can also be a list with pr. column functions such as (1 fcn1 2 fcn2 ...), where fcn1 is applied to column 1 and so on.