Marketcircle has released Billings 2.5.1, the latest version of its time tracking and invoicing software. Changes in version 2.5.1 include: rather than running timers for several clients simultaneously, v2.5.1 gives you the option to pause a running timer when a new one has started; ability to bulk edit comments in working slips; automatic notification on potentially invalid time slips; better client list sorting; and more. Billings is priced at US$74.