Excellent. Note that the GUID they use ends with '0FF1CE'. How l33t.
Also, it's not just a base64 encoded string, it's a base64 encoded C string, complete with null terminator (the AAAA at the end is a dead giveaway).
For my Office (2003) the license was split over 6 string entries (instead of the binary entry 2007 uses) named 'Current1' etc, and doesn't have the l33t GUID.
I've replaced my one with TgBvACAATABpAGMAZQBuAHMAZQAgAAAA, which comes out as 'No License'.