parsing markers into api map from external file.

hi,

i'm having a little trouble with the following situation:

i'm havaing a database with ~2000 places that have gps data and i want
to show them on an api map.
in the google maps api documentation i read that it's possible to parse
an external xml file into the google map, but the example xml file only
contains the gps data, no further information:
<markers>
<marker lat="37.427770" lng="-122.144841"/>
</markers>

i want to call a site whenever a marker is clicked and need to pass at
least the ID of that particular spot.
(i.e. http://mysite.com/description.php?id=123 )

is it possible to include such information into the XML file and how
will it have to look ?