As bitcoins increase in value, you will start to see amounts such as 0.000057 BTC in everyday use. As discussed here on the forums, eventually we will need to move the decimal place. When we do, we must create a three-letter currency code, one that does not already conflict with ISO 4217 currency codes: http://www.xe.com/iso4217.php
One proposal floated on IRC is "UBC", representing 1e-6 bitcoins. Rather than the full 1e-8, UBC would leave two decimal places to mimic familiar behavior in other currencies.
Thus, 0.12345678 BTC would become 123456.78 UBC. The current TX minimum-fee (0.01 BTC) is 10000 UBC and the proposed new minimum (0.0005 BTC) is 500 UBC.
Q: Why not "satoshis" or "nanocoins" or other alternatives?
A: The project has invested 2+ years into the marketing of the word "bitcoins", and that should not be abandoned.
Q: Should it be "uBC"?
A: No; ISO standards and currency software want ALL CAPS.
