Bug report, 152, minecart tracks.
When placing tracks north/south: Normal tracks line up with each other pretty much as-expected. Trying to place tracks adjacent to each other – for example, 6 lines of tracks in 6 spaces – "works" if you place every other one first. Until you get to the ends. The ends will insist on turning to connect. This is all proper behavior.
The bug: Attempting to place powered rails, which won't turn, works on the first "every other" spacing. As soon as you place the missing powered rails, even though they are connected north/south to other tracks, they will turn to all face east/west to touch each other.
When placing tracks east/west: Normal tracks sometimes line up with each other, and sometimes run north/south. Placing powered rails at the end will work, if the rails face the right way. That is not guaranteed.
Video shows all these issues: http://youtu.be/dnBLSwBGyqk
Note: Neither direction lines up as-expected. Both directions show different errors. Lining tracks north/south results in powered rails ignoring their existing connections. Lining tracks east/west results in both normal and powered tracks arbitrarily going north/south for no apparent reason.