It appears that Dems and Republicans will all try to field false candidates to run against one another in primaries before recall general elections are allowed to happen.
Republicans announced their plan first, and after a few days of discombobulation and shock, Dems and their allies are now scrambling to gather enough signatures to put primary opponents up against Republicans to even the score. One caveat: the same circulators can't gather signatures for two people. There's a mad scramble to get people signed up to circulate within each camp.
The GOP has forced the Dems into this action - if the Dems don't field candidates in response to the initial GOP move, GOP voters would be able to vote en masse in the primary against the real Dem candidate. We Are Wisconsin has a good outline of what this all means on their website.
My opinion: this is the next level. Just when you think things won't get crazier and more intense in this fight, something like this happens - and the repercussions will be significant. I'll be out in the field watching the events unfold this weekend and will update more afterwards.