This seems to be another bogus warning:
2010/01/19 09:26:47 WARNING (MultiPolygonRelation): Cannot join the following ways to closed polygons. MP-Relation http://www.openstreetmap.org/browse/relation/302408
I did josm 'http://www.openstreetmap.org/?lat=64.73925&lon=29.49075&zoom=18' selected the relation of the node and downloaded all members in the relation editor. Each 'inner' member (island) consists of a closed way according to the relation editor. (It shows closed loops next to the members.) The 'outer' member (coastline) consists of 7 ways, which form a closed loop. 6 of the ways are 500 nodes and the last one is 218 nodes.
To me, the data seems fine.
Marko
Marko, there are some problems with mp code and osmosis/tile splitter. In your case I think it's the tile splitter. The splitter puts only parts of the ways that crosses the tile bounds to the resulting tile file. The handling for these incomplete mp ways on the tile border is on the list which must be implemented next. By the way: did you see that lake with the old mp code and the same splitter bounds? WanMil