Is there something I can put into the Google Contacts entry for someone that will link it to their Twitter handle? I have tried putting “@JohnDoe” into an IM-type field I’ve named Twitter, but that didn’t do the trick.
Both Facebook and Twitter contact sync stopped doing anything useful sometime recently (ICS?). They no longer provide a meaningful between your phone contacts and the actions provided by those clients. I think this has to do with changes to the Android API that for whatever reason these companies have not adapted to.
There is a stop-gap solution for Facebook using a third party app such as Contact Sync for Facebook or Friends Sync* but I don't know any solution for Twitter other than the hack-it method of having a URL listed and using the web client.
* This publisher also has other sync apps for foursquare, flickr, and others.