Due to recent reports of theft activities by hackers, is cyber security is an on-going concern for Bitcoin and are active measures being taken to improve security?
You should always be aware of scam/hacks/thefts. Millions of dollars is stolen from 'regular' netbanks every year, so this is not really a "bitcoin-only" problem.
Bitcoin is based on crypto, so use this to protect your wallet. You can secure bitcoins way better than any other currency, but if your storing large amount of bitcoins in a unencryptet 'hot' wallet on a unsecure server, then your begging some hackers to steal your bitcoins.
You can find a lot of tips about securing your wallet here: https://en.bitcoin.it/wiki/Securing_your_wallet
But heres also some simple tips:
Encrypt your wallet (the build-in encryption is (almost) unbreakable as long as you choose a strong passphrases)
Never store all your bitcoins in a 'hot wallet' (unless your going to spend them all at once)
Make sure to take backups, and store them securely offline! (bitcoin-qt has a build-in key pool).
And make sure to keep your computer clean for malware