After switching over to SVN, which (fingers crossed) has finally fixed my intermittent black terrain issue, but since updating to the most recent SVN version, any wonders being built in my cities are no longer visible. Has anyone else experienced this, or have any idea on how I could fix it?

Look in the player documentation thread

Ahh, found it. Thank you so much!

Yep, working perfectly again. Oh my god, that is so awesome. I was afraid it was some bug that was going to require a new game, and given that I hadn't built my first wonder until halfway through the classical age, when I noticed it not there, that is not something I was particularly looking forward to doing.