Re: A bug?

As others have already mentioned, that's the way API version 2 works.

Unlike version 1, the markers always stay in the region of the map
between -180 and +180 longitude. If you pan the map so that you're
looking at the region between 180 and 540 longitude you'll not see any
markers.

If you think that's a problem that you need to deal with, you can add a
moveend listener that checks to see if the map centre is outside the
range -180 to +180 and if so recentres it by adding or subtracting 360
longitude.

In version 1, the markers were always drawn of the same copy of the map
that the map centre was in, which caused some problems when there were
points near the International Date Line.

I guess that recentring on moveend would cause something like the v1
International Date Line effects to come back.

--
The Blackpool Community Church Google Map API Version 2 Tutorial
http://www.econym.demon.co.uk/googlemaps2/