yes! So this. I agree; Let's see some constructive criticism and ideas for how to improve the LightTable idea, instead of just trying to shoot it down as 'not novel'.
The instant evaluation model doesn't play nicely with side-effects. Exactly where side-effects occur can be difficult to determine, there's no simple way to work around this.
This is less of a problem in Clojure, thanks to its immutable data structures, but they're not a panacea. I'm also not sure how well this would work in JS and Python, the other languages that Light Table intends to initially target.
One possible solution is to have hooks into side-effects: you could display console output or logging alongside the instant evaluation. The real difficulty is network communication: even if you're okay with actually sending requests over the wire, there's an awkward balance between visibility and generality. Something like libpcap [1] is very general, but gives minimal insight into the content. Hooking into a particular HTTP client library gives you a lot more visibility into what's going on, but you'll need to do this every time you want to use a new library.
What is important is the execution and new wrinkles in the CURRENT iteration - NOT whether something vaguely or even pretty similar was attempted or proposed at some point in the past.