e.g. try this: http://maps.google.co.uk/?q=http://www.chiark.greenend.org.uk/~janetmck/oucsmain.kml
For me, this example (very simple KML) shows my pointer, but the map doesn't show -- I just get grey tiles saying "We are sorry, but we don't have imagery at this zoom level for this region. Try zooming out for a broader look." Zooming out doesn't make any difference.
This used to work. We haven't changed anything. I can't find a single KML file on the web which does work in Google Maps. Have Google broken this? Am I going mad?
ETA: In fact, it's not just KML. Any search in Google Maps seems to be broken for me, e.g. searching for 'Oxford' -- it finds it, it shows the pics and so on in the sidebar, it puts a point on the map, but doesn't show any map tiles.
And while doing searches for Oxford I got a sponsored link from Google pointing me to "Oxford Homeopath". Grrrr. More than homeopathic amounts of map data, please, and fewer sponsored links to charlatans.
ETA 2: Really, no amount of zooming out seems to make the map appear for me. :-(