I've got a vCenter 5.5 build 1378903 install and a host I just upgraded to 5.5 build 1331820.  I did the upgrade by putting it in maintenance mode, detaching my PowerPath/VE 5.8 extension group from the host, attaching my new PowerPath/VE 5.9 group to the host, disabled lockdown, applied all outstanding ESXi 5.1 patches and reboot, applied the PowerPath/VE 5.9 patches and reboot.  I used 'rpowermt check_registration' to verify it was okay and it seems to think it is.

However, having not taken it out of maintenance mode yet for fear something is wrong, I checked the EMC VSI tab in my vSphere Client and it reports this at the top of the screen in a bright color:

The PowerPath/VE service is not managing any LUNs on this host.

If I use 'rpowermt host=192.0.2.1 display dev=all' it seems to think things are working:

Pseudo name=emcpower1

VNX ID=1234 [LUN1]

Standard UID=naa.1234 [BLOCK_LUN_20]

state=alive; policy=CLAROpt; queued-IOs=0

Owner: default=SP A, current=SP A       Array failover mode: 4

==============================================================================

--------------- Host ---------------   - Stor -  -- I/O Path --   -- Stats ---

###  HW Path               I/O Paths    Interf.  Mode     State   Q-IOs Errors

==============================================================================

   1 vmhba32                C1:T6:L0    SP B4    active   alive      0      0

   1 vmhba32                C0:T7:L0    SP B5    active   alive      0      0

   1 vmhba32                C1:T4:L0    SP A4    active   alive      0      0

   1 vmhba32                C0:T5:L0    SP A5    active   alive      0      0

I would assume the output would have been empty if PowerPath was not actually managing I/O to that LUN?

On the Configuration tab, Storage, 'Devices' button, pick one; in the lower window "Device Details" it shows owner as PowerPath.

My other PowerPath/VE 5.8 hosts on the EMC VSI tab continue to state "Found PowerPath/VE version 5.8 (build342) installed on this ESX host..."

I dont want to take it out of maintenance mode and risk live guests moving back to it if something is actually wrong with PowerPath.  Anything else I can check?