A couple of additions or qualifications:
Alfredo Gonzalez has been injured parts of at least two years in the past, and his stats at the plate should not be held against him. This year's performance is probably more indicative.
Roberto Pena has appeared in 2 games at 2B and 1 at SS, but all three were late inning switches; as far as I know, he is not on the Biggio career track.
Jamie Ritchie has indeed split time between C and 1B, but has spent far more time at 1B. I have not heard reports, but he does not seem to be a long-term solution behind the plate.