I just read Ruslan Spivak’s blog posting on how to get Ctrl-s (which is bound to incremental-search-forward in Emacs) working to search incrementally through the command history in Bash.
Normally this behaviour is shadowed by a terminal flow-control key binding. To turn that off and ‘reveal’ the search-forward function, simply type
(of course, by adding this line to your ~/.bashrc file makes it permanent).
Great to get this working! Thanks Ruslan.