I rebooted and confirmed; indeed the older L5520 is still the processor being used on my particular linode:

<snip>

    processor       : 7
    vendor_id       : GenuineIntel
    cpu family      : 6
    model           : 26
    model name      : Intel(R) Xeon(R) CPU           L5520  @ 2.27GHz
    stepping        : 5
    microcode       : 0x11
    cpu MHz         : 2266.746
    cache size      : 8192 KB
    physical id     : 0
    siblings        : 8

</snip>