[pro] How to interact with a running lisp instance?

[aerique at xs4all.nl]

On 17 dec 2010, at 22:15, Eli Naeher <enaeher at gmail.com> wrote:
> Right now I usually have (under screen) one instance of Emacs for
> personal projects (for which I try to use the latest Slime and Swank)
> and one for work (where they do not get updated so frequently), and
> sometimes I need to start a third instance if I am doing work on an
> older maintenance branch of the software. It seems like there should
> be a way to switch between Slime versions within the same running
> Emacs, but I have yet to figure it out.

Not a direct question to Eli, but why is Slime so version specific  
anyway?