Is there bitcoin implementation in python or C#? I want to play with the implementation to better understand the inner workings of Bitcoin. I'm familiar mostly with python and C# and found no clients in either of the languages. My C skills are rusty because I haven't done any C in last decade.
There isn't yet a complete implementation AFAIK, but there are different libraries that implement bitcoin features (wallets, keys, utilities, 

Depends on whether you want an implementation of bitcoin network protocol or wallet or just an overlay on top of the JSON-RPC interface of bitcoind.

Useful code on github:

https://github.com/jgarzik/python-bitcoinrpc - Python interface to bitcoin's JSON-RPC API

https://github.com/etotheipi/BitcoinArmory - Python-Based Bitcoin Software

https://github.com/gavinandresen/bitcointools - Python-based tools for the Bitcoin cryptocurrency system

https://github.com/jgarzik/python-bitcoinlib - Bitcoin library

https://github.com/spesmilo/electrum - Electrum thin-client

https://github.com/spesmilo/electrum-server - Electrum server

https://github.com/spesmilo/sx - Python CLI tools