Well, if we really wanted to we could probably hack something together along the lines of the Project Orion designs right now, but it would be hugely expensive and pretty messy so I can't see anyone doing that.

http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propul...

I suspect if we do send out interstellar probes they will be tiny rather than flying battleships:

http://en.wikipedia.org/wiki/Starwisp