Well yeah even between blockchains is possible with multisig of some kind apparently.
The hard part is anywhere that touches fiat.
Indeed. In terms of functionality it is roughly same as OpenTransactions (less feature-full, of course), so it does not solve 'fiat' problems.
I believe that Ripple might solve 'fiat problem', but Ripple requires entirely different infrastructure. I'll implement it later, next month, maybe
So okay, if a bunch of coins each having 21,000,000 coins each just like bitcoin all want to try using this coloured thing, how do they go about issuing their 21,000,000 coins each as colours on your system?
According to the original spec we can define a split in a genesis transaction which issues new type of currency/asset. E.g. we declare that 0.001 Bitcoins descending from genesis txn are 1 RedCoin.
But this is just for display purposes, of course, backend software counts everything in satoshis anyway.
So we would observe loss of precision, i.e. currencies which are introduced via split would have a relatively larger quantum.
This would be much less of a problem if base currency has potentially infinite monetary base. (E.g. 50 coins mined forever.)