Sharepoint 2010 is here with powershell integration making it easy to change the passwords for sharepoint managed accounts whose passwords are not set to change automatically when nearing expiration. 

1) Change the password in AD for service account.

2) Update the password for the service accounts in the sharepoint 2010 farm .

Here is a quick run through

Change the password in AD for service account.

I assume  you can log on to a windows 2008 r2 server in domain where service account exists , you have rights to change the password for the service account. I am using a fictitious account  by the name _svc_acct for this scenario

a) After logging into a server in account domain  launch powershell

b ) Load the AD module

import-module activedirectory

c) Assign the account name to a variable

     $account="_svc_acct"

d) set the password ( please note this as we will be using this in the next section)

     Set-ADAccountPassword -Identity $account -OldPassword (ConvertTo-SecureString -AsPlainText  "xxxx" -Force) -NewPassword (ConvertTo-SecureString -AsPlainText "xxxxx" -Force)

e) Check for successful update of the password updation  ( out put should show recent tiem stamp)

Get-ADUser $account -properties * | select PasswordLastSet

For engineers who do not have windows 2008 r2 machines , you can always change password through your normal process.

Update the password for the service accounts in the sharepoint 2010 farm .

 a) Log on to the CA in the Farm, launch powershell.  Assign the new password from step d in the above section to a variable also store the account to a variable

$account="_svc_acct"

$securepassword=convertto-securestring "xxxxx" -asplaintext -force

b) Retrieve the Sp managed account   and pipeline it to the set-spmangedaccount cmdlet

Get-SPManagedAccount Domain\$account | Set-SPManagedAccount -ExistingPassword $securepassword -UseExistingPassword -confirm:$false