Using dates for plotting

Dear R-Users!

I have the following data:

runs

dates kms
1 2004-01-15 12:00:00   9
2 2004-01-16 12:00:00  10
3 2004-01-17 12:00:00   5

class(runs$dates)

[1] "POSIXt"  "POSIXct"

Is it possible to _easily_ plot these data with real dates shown as
tick marks on the x-axis? Perhaps even when the days are not
continuous but with missing days in between?

Thanks in advance,

  Christoph.

Christoph Lange
MPI fuer biologische Kybernetik  |Phone: +49-7071-601-607|
Postfach 2169, D-72012 Tuebingen |FAX:   +49-7071-601-616|