When building ORBit-0.5.12 (rawhide of jan 14th), i noticed that the libORBit.la file is not included in the %files part of the .spec file. This causes every package that depends on it for building to fail.. (i noticed while recompiling control-center & evolution). the fix is simply to include %libdir/*.la ;-)
It should only cause builds to fail if you have previously built another library against a version of ORBit that _did_ contain *.la I haven't decided yet if it's a bug to include .la or a bug to leave it out... they mostly just cause problems and have no apparent benefit...
OK, for now at least I've adopted the policy of "no .la files"