I really don't see many other bicycle commuters on my route. The ones I do see are usually on the sidewalk (I ride on the road). Sometimes a fixed gear teenager, sometimes an Hispanic on a BSO mountain bike . . . overall very rare to have a conversation opportunity.
However, part of my commute is on the Los Angeles Metro and I have talked with several other cyclists while we were on the train. Most don't want to talk (ear buds in), but some do. One Asian guy I used to talk to fairly often on the Metro but haven't seen him for quite a while.
Rarely a non-cyclist on the train will strike up a conversation, and that's cool too. Big picture though . . . not much.
Rick / OCRR