The current mongod and webinterface show information about the current MongoDB version.
I would like to suggest to split the current details into information about the build, and information about the current system (using uname -a).
For example:

build
db version v1.6.5, pdfile version 4.5
git hash: 0eb017e9b2828155a67c5612183337b89e12e291
sys info: SunOS fhm8e4dc.joyent.us 5.11 snv_89 i86pc BOOST_LIB_VERSION=1_38
system
uptime: 4696 seconds
sys info: SunOS mongodb.example.com 5.11 oi_148 i86pc i386 i86pc BOOST_LIB_VERSION=1_46

In the current version, I would expect 'sys info' to be the system that runs the daemon, since also uptime is mentioned. But it actually shows the 'sys info' of the system it was built on, which was kind of confusing.

An other option would be to change 'sys info' into 'sys built'