So recently I went to make a copy of a database that had CDC enabled for certain tables. It was a non-production copy, so I didn't need CDC in play. However because the original database had CDC I found that the Transaction Logs couldn't be truncated because there was stuff that hadn't been captured yet.
Luckily I found this Microsoft article: http://msdn.microsoft.com/en-us/library/ms173775.aspx
After executing the following command I was able to truncate the log:
EXEC sp_repldone @xactid = NULL, @xact_segno = NULL, @numtrans = 0, @time = 0, @reset = 1