I started crossposting to facebook in may 2010 and google plus in august 2011. There have been 1042 facebook and 360 google plus comments in that time. No real pattern jumps out at me from the facebook comments (10 post moving average, x axis is posts where 0 is the first facebook crosspost):

Over the period I've had both facebook and google plus comments they've been mostly correlated:

The posts with the most comments have been:

facebook:

1. 2011-09-13 Boston Hall Search (25 rounded)
2. 2011-09-12 Boston Needs a Centrally Located Weekly Contra Dance (25 rounded)
3. 2011-07-31 Contra Dance and Sexist Terminology: Two Perspectives (25 rounded)
4. 2011-06-18 Boston Apartment Prices Map (25 rounded)
5. 2011-05-07 Models Of Contra Dance (25 rounded)
6. 2011-03-18 In Light Of Crashes, We Should Not Make Buses More Safe (25 rounded)
7. 2011-03-11 Donate Money, Not Time or Stuff (25 rounded)
8. 2011-02-15 Making mbtaplot more useable (25 rounded)
9. 2011-09-04 Expected Value and the Two Envelope Problem (24)
10. 2011-07-19 Singular They And Social Networking: Google Plus (22)

google plus:

1. 2011-08-07 Calling With Lights (30)
2. 2011-10-24 How Many People Will There Be? (19)
3. 2011-08-08 Negative Income Tax (18)
4. 2011-08-29 Commuting (16)
5. 2011-09-23 An example landlord letter (12)

I'm not very good at tagging things. Half of tags I've only used once, and I tend to slap the most frequently used ones on too much:

The top tags are:

1. tech (78)
2. contra (52)
3. music (47)
4. giving (32)
5. transport (28)
6. ideas (27)
7. money (26)
8. mbta (24)
9. python, calling (19)