Any thoughts on how to fix this? Or if this is a bug in Steam?
Have you disabled the Steam runtime? Pango should be used from there and not from your system.
I ended deleting $HOME/.steam directory, then renamed the Steam directory that had my games in it to "Steam.bak". Uninstalled Steam, then installed the latest DEB from Steam (downloaded off their site). It updated to the newest client, and then I just renamed the "Steam.bak" directory back to "Steam" then added it as a library in Steam itself. Maybe just a bad version?
Nothing extracted yet.
After a new update, I get a popup stating "Fatal Error: Failed to load steamui.so" .. A little more investigation, and it seems it's relying on "pango_font_map_changed"?
/usr/lib/i386-linux-gnu/libpangoft2-1.0.so.0: error: symbol lookup error: undefined symbol: pango_font_map_changed (fatal)
I'm running Ubuntu 64bit 14.04.