It's not as rampant as before where there would be one every day at least at times.
As for spambot protection, the situation on the Bay12 forums (which uses the same forum software as this one, same version even), is pretty good and while spambots still appear, they don't get rampant like we used to have before the forum software upgrade.
100% spambot protection is probably impossible without the adminstrator okaying every single registration. Dan doesn't have that kind of time.
I don't know what the effectiveness of the various methods are.