After reading this thread, I decided to look into things a bit more, it does seem like bots are already causing a minor disturbance on some sites.
I thought there would at least be several years before bots played NLHE well enough to be profitable, but some threads on twoplustwo.com suggest that there are already bots on PartyPoker
that are crushing the microlimits.
It makes me feel pretty disappointed. Maybe online poker will be dead very soon (real money games anyway).