Chuck, I read your post regarding Jono and the EFF choosing Twitter over Identi.ca, and ask the same questions you are: "If you're about Freedom and Liberty, then why choose a proprietary standard when an open one exists?" However, at the bottom of your post, you mention that you don't mind proprietary software, saying that there are many features which proprietary brings to the table that Free Software does not, even if this is becoming more and more rare. Well, let me refer you to a quote by Eric S. Raymond:
When you tell me I should give proprietary software a fair technical evaluation because its features are so nice, what you are actually doing is saying "Look at the shine on those manacles!" to someone who remembers feeling like a slave.
I use Identi.ca for two reasons: it's Free Software, licensed under the GPL and it's based on an Open Standard. I use Jabber for the same reasons. I use everything in my life for those very reasons. Free Software and Open Standards. If the software doesn't fall under one of those two categories, it doesn't have a place on my computer. Like Eric S. Raymond, I am anti-proprietary software.