vsphere management assistant (vMA) 5.1
you need to install a new vMA virtual appliance for 5.1 (a 4.x appliance can not be upgraded to 5.1).
vMA 5.1 is backwards compatible with 4.1 hosts. on initial power-on of the new appliance i received an error similar to “…network has no associated network protocol profile”. evidently, the new appliance is configured as a vApp by default. i had no interest in vMA being a vApp and so on the VM itself, i went to Edit Settings->Options->vApp Options and chose disable.
final note, the password requirements for the vi-admin account seem to be stricter than before.
update 12/6/2013:
vma upgrades are no longer done through the command line. instead you will need to browse to https://vma:5480 and go through the update process there after mounting an iso to the appliance.
update 1/21/2014:
there’s the upgrade feature i mentioned in a previous update, but oddly enough it’s not used in the transition to vma 5.1 to 5.5. the vma 5.5 appliance has to deployed from scratch. source: https://www.vmware.com/support/developer/vima/vma55/vma_55_relnotes.html#priorreleases