The latest version of XNA only requires .NET framework 4. XNA 4.0 refresh was published well over a year ago so I have a feeling a new version won't be coming out any time soon. Not that it would matter as far as my game is concerned. I'm not upgrading frameworks and possibly gumming up my game halfway through development. 4.0 kinda screwed some of my older projects out of ever being worked on again.
In other news, I worked on drawing some space station parts over my lunch break. Space stations will be using the same format as ships so most of the code will be the same. They just won't move. Much. Well, outside of orbits that is. That's the funny thing about space, everything is always moving. In fact, now that I think about it the only thing that won't me moving is the central star in the star system. Unless I throw in an imaginary super massive black hole a few thousand light years away but then I think things would start getting pretty ridiculous.
Edit: Also toying around with the idea of player owned space stations. The economy's not going to be as complex as what you might see in the X series games, just fixed commodities at varying prices depending on where you go. If you haven't played any of them, the X games have a living economy that's constantly changing. Ships bring in lots of power cells and the price drops way down. It's a nice concept but it's a lot for the player to have to keep up with. And since my game isn't going to be tracking every single ship across the entire galaxy all at once, it's just not going to happen. That's part of the reason the X games have such high system requirements.
Where was I? Space stations! So yeah, you could build space stations but not really to sell stuff from. I'm thinking something more like a base of operations where you can store your extra ships, ammo...slaves? I don't know. Still thinking on it. In any case this won't be something added until I start working on the full version.