I didn't move one of my ships in Sinuwan last turn
and a planet has moved onto the same hex as it.
When I click the hex once I see the ship,
when I click it again I see the planet .
Should this happen?

The ship should really bump out of the hex...on the list.

I could see some cool ideas for "landing ships."

on a similar note, I think you can land a ship on a planet (or sun as well... haven't exactly tried to) by trying to move 1 hex past it... but you fall short 1 hex due to the ships available speed... for the most part I just go on and never actually tried to do it, but for the most part it looked like it would

--edit:
on another note, using the plus day option, I found a system where 2 planets would collide into each other... lol, and they just stacked on top of each other...

They are not on top of each other. Check their orbits.

It's the lensing effect of ripspace.

heh, was wondering if I could actually find an example again... then I realized... right now in the system coraisle (43,41), coraisle 1 and 3 are on top of each other... (up and to the left of the sun) I noticed it when I hit the plus day button and all of a sudden the system gained a planet, lol. (help, the planet clones are attacking!!!)

well, either way, when it happens, one of the planets is completely unselectable without hitting the minus or plus day option till it becomes visible again.

... lensing effect? lol

anyway, on another note, yes, you can force your ship to land on a planet by having it fail to go far enough to get off the planet (I just used the cumulative move feature to get it like that, though extremely tricky on planets with large gravwells...)

Just patched the server so the ship should get bounced into a different hex.