Xero has officially released it's WIP Ledger, allowing firms to track their WIP through the platforms Practice Manager. Best of all, according to the announcement I received it is FREE to Silver+ Xero Partners.
According to Xero, the WIP Ledger gives you a better view of your practice activity by showing you the exact amount of unbilled time and costs for each job. In addition to the practice activity "snapshot", the WIP ledger comes with some new reports like the Job WIP balances report, which gives you an accurate breakdown of unbilled WIP at any date, and the WIP Control Report, which provides a practice-wide view of WIP lockup and movements.
You can find the full details on the Practice Manager release on the company's blog.