I was wondering about this myself. There's a fixed total supply of bitcoins, and a non-zero rate of loss can be expected - this doesn't seem like a good long-term combination.
The Bitcoin protocol allows for 8 decimals worth of divisibility, meaning that there are actually 2.1E16 or 21 quadrillion
"units" (aka "Satoshi's") available.
And the divisibility can be extended. The 8 decimals are largely just because the current client(s) only understand it to that degree.
It sounds like a few good "money burning" viruses and you would double the value of bitcoins by reducing supply. Back up your wallet!