Yes they have been doing this for a while.. The latest set of attacks are using it more. I
have seen attacks where machine A goes for account "foo, foo1, foo2" and then machine B does
"foo3, foo4, foo5" and then machine C goes for "foo6, goo, goo1" and machine A tries again
(well its a lot bigger than that but just logging in once and coming back an hour later is
enough to get past most public ssh servers fail2ban systems.) Add onto that a lot of users
think Q1w2e3r4 is a good password and are sure to get some account on a university or big ISP
sometime.