The last link in my post covers this stuff pretty well. The speed isn't actually infinite, just close for some cases. Yeah, for about 8 minutes we'd be leaving orbit for a reason we couldn't visibly detect.

Being able to teleport a star would be fun.

I saw somebody say perpetual motion / free energy generation would be possible using the portals from Portal, and that this was somehow shocking. It apparently didn't occur to them that it wasn't shocking because we don't actually know a way those portals could be possible.