a sample link posted to "nerd forum" in Finland in November '07 already:
http://maps.google.fi/?ie=UTF8&ll=53.883297,109.105225&spn=1.16888,2.570801&t=h&z=9&om=1

According to the thread the line continues as yellow when scrolling to the West.
Source (Finnish language) at
http://keskustelu.plaza.fi/muropaketti/bbs/t470796,100

Probably the border of the satellite image.

Oh, the passage to the parallel universe.

Thanks, it sounds that it is a good explanation.