2.0 - not worth even bringing up. 11 out of 10 people you talk to didn't feel a thing. You're just excited that the SCEC website showed it to be a quake and not a bus driving by this time. You feel suddenly vindicated for using that as your homepage since someone showed it to you a year ago. In general, at 2.0, no one except other n00bs will care.
3.0 - people start getting excited. IMs / texts "omg did u feel that? was that a quake?". Cue links to SCEC. Everyone has ~90 minutes of excitement refreshing page looking at the aftershocks. Productivity decreases across the Southland. In general, you'll find people are excited when there hasn't been any noticeable seismic activity in a while or when it's been very active. (Tip: if you're quick enough, immediately sign off after first "omg did you feel that?" IM; it can really freak people out.)
4.0 - cue call from parents. Regardless of time of seismic activity, call will usually occur the following butt crack of dawn:
Parental Unit: Are you okay? Your aunt called and said that she saw on the news that you guys had an earthquake. Everything okay there?
You: What? What time is it? Why is the sky orange? What?! Uhm, I guess I slept through it. Good thing you called me to make sure I woke up 5 hours later. kthxbye
5.0 - local news reporter films in empty grocery store parking lot. Poor bastard is reduced to pushing and then filming "runaway" cart. Roll stock footage of lone knocked over box or bottle in store that may or may not have been like that before earthquake. Cue interview with geologist who clearly wants to smack shit out of reporter asking retarded questions. n00bs will often freak out at this level and are usually the ones reporter will interview asking the same two stupid questions: "Where were you?" and "What did it feel like?" After watching this for the umpteenth time, you become dumber and can't understand why you didn't change the channel 15 minutes ago.
6.0 - you're wondering if you kept any of the bottled water in the last move. TV is preempted for hours. Cue interview with geologist who seems to have an inappropriately happy and excited affect while discussing what caused a home to partially collapse and slide down a hill, trapping 50 school children in the daycare center below.
7.0 - EVERYBODY PANIC
Also: At some point someone will invariably refer to "earthquake weather" because his grandmother swears by it and tells colorful, anecdotal stories as backup. For the love of the gods, this is an urban legend. No one in science with any credibility in the history of forever has found a correlation between changes in weather and seismic activity... EVAR. Smack your grandmother next time she brings it up. It's the only way she'll learn.