The kohonen package version 2.0.0 is described in 
R. Wehrens and L.M.C. Buydens, J. Stat. Softw. 21(5), 2007

Changes in version 2.0.1:
  - fixed a bug in unit.distances: for rectangular maps the toroidal
    argument was ignored. Updated the corresponding example as well.
  - added an argument 'n.hood' to functions som, xyf, bdk and
    supersom, so that the user can decide what distance measure to use
    when calculating distances between units. Useful to compare the
    results with other som implementations.
  - specification of radius as (start, stop), similar to alpha. This
    gives better control (suggestion of Hadley Wickham).
  - more sanity checking in functions som, xyf, bdk and supersom 
    (suggestion of Hadley Wickham).
  - added the J. Stat. Softw. paper and a CITATION file to the distribution.

Changes in version 2.0.2:
  - changed the 'predict.kohonen' function to take account of a change
    in the behaviour of 'aggregate' in R version 2.6.0 and later

Changes in version 2.0.3:
  - removed a bug in supersom, introduced in 2.0.1 when checking if
    the data are numeric.
  - added an example for supersom.
  - removed a bug in plot.kohcounts, arising when empty units are
    present
  - updated man files for methods 'plot', 'predict', and 'map'

Changes in version 2.0.4:
  - introduction of tricolor function
  - prediction of multiple layers
  - Y in function xyf now can also be a factor
  - any element of the data argument in function supersom can now also
    be a factor
  - added new prediction examples for som, xyf and supersom
  - uniform output of som, xyf and supersom functions

Changes in version 2.0.5:
  - Changed title of the "quality" type plotting function to
    "Distance" rather than "Similarity"
  - Extra parameter "heatkeywidth" (thanks to Henning Rust) for
    control over the size of the heatkey. Useful for cases with
    multiple plots, and probably elsewhere too.
  - Added plotting type "dist.neighbours" which shows Ultsch' U-matrix:
    units are coloured according to the sum of the distances to their
    immediate neighbours. A high distance can be interpreted as being
    on a class boundary.
  - Plotting types "quality", "dist.neighbours" and "counts" now
    invisibly return what they show.
  - Added information on the wine varieties, as well as a reference to
    the original publication.
  - Cleaned up C-code and man pages to eliminate warnings in the
    development version of R 2.9.0

Changes in version 2.0.6:
  - Added palette.name as argument to plot.kohcode
  - Function-specific default palettes
  - Changed contact address to ron.wehrens at iasma.it
  - Added visualisation of clustering of units (Leo Lopes)

Wishlist:
  - more flexible definition of distances: should be user-definable
    for every data layer.
  - identify.kohonen function: should return unit numbers that are
    clicked whether or not a colour bar is present.