Going through open source hr solutions, looking for integrated time & attendance solutions, it seems that on the very least basic time & attendance functionality is available.
OrangeHRM, catering to the SME market has the basic functionality as shown here (http://www.orangehrm.com/open-source-product-features-TandA.shtml#TandA)
A1 eHR also has some interesting news from their blog about their Time & Attendance module as found here (http://www.a1.io/a1io_blog/improving-time-attendance-in-hr-applications/). As expected the depth to cater for a global workforce of a Mid-Large organization is there.
The big news from A1 eHR is in use of mobile devices for check-in/out, this is a feature at par with some of the leading human resource applications globally.
Looking at specialized solutions, I see TimeTrex has a very specialized open source vertical for Time & Attendance. This could be very well integrated with open source hr solutions that do not have inbuilt Time & Attendance inbuilt.