over at ivanov/vim-ipython#31, @pielgrzym pointed out that vim-ipython is able to monitor and display input and output for the kernel it is monitoring, regardless of what client initiated this activity, whereas activity initiated from vim-ipython is not reflected by these clients.

This is not unique to vim-ipython, however. Both the qtconsole and console frontends currently ignore the messages that they did not initiate. In other words, if you have two qtconsoles connected to the same kernel, executing code from one of them will not affect the other one in any way.

It would be nice for the qtconosle and console frontends to periodically check the relevant channels and make this activity visible. This would certainly be a good candidate for toggle-able behavior, since sometimes you really do want to ignore what other clients are doing.