Bitcoin versions

v0.10.0 [Mar 23, 2015]
- Faster synchronization
- Transaction fee changes
- RPC access control changes
- RPC Server “Warm-Up” Mode
- Improved signing security
- Watch-only wallet support
- Consensus library
- Standard script rules relaxed for P2SH addresses
- bitcoin-tx
- Mining and relay policy enhancements
- BIP 66: strict DER encoding for signatures

v0.5 beta [Dec 20, 2011]
- Check all transactions in blocks after the last checkpoint (0.5.0 and 0.5.1 skipped checking ECDSA signatures during initial blockchain download; this was not a security vulnerability).
- Cease locking memory used by non-sensitive information (this caused a huge performance hit on some platforms, especially noticable during initial blockchain download).
- Fixed some address-handling deadlocks (client freezes).
- No longer accept inbound connections over the internet when Bitcoin is being used with Tor (identity leak).
- Re-enable SSL support for the JSON-RPC interface (it was unintentionally disabled for the 0.5.0 and 0.5.1 release Linux binaries).
- Use the correct base transaction fee of 0.0005 BTC for accepting transactions into mined blocks (since 0.4.0, it was incorrectly accepting 0.0001 BTC which was only meant to be relayed).
- Don’t show “IP” for transactions which are not necessarily IP transactions.
- Add new DNS seeds (maintained by Pieter Wuille and Luke Dashjr).

v0.4.0 [Sep 24, 2011]
The main feature in this release is wallet private key encryption; you can set a passphrase that must be entered before sending coins. See below for more information; if you decide to encrypt your wallet, WRITE DOWN YOUR PASSPHRASE AND PUT IT IN A SECURE LOCATION. If you forget or lose your wallet passphrase, you lose your bitcoins. Previous versions of bitcoin are unable to read encrypted wallets, and will crash on startup if the wallet is encrypted.
Also note: bitcoin version 0.4 uses a newer version of Berkeley DB (bdb version 4.8) than previous versions (bdb 4.7). If you upgrade to version 0.4 and then revert back to an earlier version of bitcoin the it may be unable to start because bdb 4.7 cannot read bdb 4.8 “log” files.