On May 3, 2007, Scotland used STV for the first time, where it was used for their local government elections. The City of Glasgow has published all the ballots from its STV elections and you can download the ballots here.

OpenSTV includes the Scotland STV rules and was successfully validated, over hundreds of tests, against the software actually used by Scotland. You can verify the official results by downloading the ballots from the link above, running the election with OpenSTV, and comparing OpenSTV's results with the official results.

Unfortunately, Scotland held STV and MMP elections on one ballot paper, which confused many voters and caused a significant number of invalid ballots. A positive sign, as discussed in this BBC article, is that many fewer ballots were invalid for STV than for MMP, showing that voters are capable of ranking candidates even when the ballot is poorly designed.