Are there already several ways to do "smart contracts" with cryptocurrencies? I have heard a lot of "buzz" about Ethereum, but apparently its 1.0 version won't be released for a while yet.

I have heard a lot of talk about "smart contracts" from people who admire Szabo, but I haven't seen many implementations.

I notice that Ripple lists "contracts" under "future" features, which seems to imply that they are not ready for use yet.

https://ripple.com/wiki/Main_Page

The one implementation I have seen is at :

http://erights.org/

Are there any other, more popular ways to implement "smart contracts" that are already in use?

Thanks
There is Orisi.org - you can read the whitepaper here Orisi.org/distributed oracles whitepaper, and run an example Timelock contract here.

The differences between distributed oracles/Orisi and Ethereum are:


Orisi works on top of Bitcoin, so there are no other currencies inbetween
oracles can reference external inputs, so you can create a contract that finalizes based on weather/currency prices, or even mechanical turk
it's available today
on the other hand, it has a different trust mechanism than Ethereum - oracles are supposed to be run by trusted independent parties. So, instead of proof of work, you have a proof of identity.


You can also read this blogpost by one of the bitcoin core devs: bit-thereum. It explains why m of n oracles might be a good solution for contracts.