Linux biometrics is all over the place... pretty much the same as the HW.
since you seem focussed on fingerprint comparison.
More general biometrics: http://www.linuxbiometrics.com/
since there are many things you can measure.
The best bet, like with all hardware, is to find out what models are available, then google them.
Checkin management is in addition. The easiest bet is just to have whatever scheme you'd usually use sans biometrics.