Strategies against Bitcoin With the recent increase in articles about the threat of Bitcoin vs central banks, government and other authorities over the money supply, I am wondering how well authorities are prepared and actively dealing with the situation. 

Yes, most are probably aware of it by now. There have been some official statements by several agencies. Most notable I could find are the ECB: Virtual Currency Schemes (PDF, European Central Bank - October 2012), U.S. Senators seek crackdown on "Bitcoin" currency (Reuters, June 2011) and FBI Fears Bitcoin’s Popularity with Criminals (Wired, May 2012)

Is there any proof that serious plans are in the works to 'crackdown on Bitcoin' - either directly by creating laws or indirectly by influence on the market?
just some ideas:

Strategies could be attacking the trust structure of bitcoin:


Buying large quantities of bitcoins and dropping them on the market causes it value to fluctuate and make it appear weak  
hacking peer sites (like mtgox), or bitcoin users directly (via trojans, etc.) leaves insecurities on where to use it  
influencing media to emphasize about the dangers of bitcoin (selling drugs, weapons, etc.) will make it less accepted in society by creating fear
creating various alternative currencies, flooding a lot of misleading information, to weaken the marketing of bitcoin by confusion and information overflow


Could be attacking the technical side:


Creating big amounts of powerful ASICS and use them for false verifications
stuffing the blockchain with spam information and useless transaction, making it to big to handle
Blocking and filtering traffic from bitcoin clients, will make it necessary to use TOR (which could be also blocked in certain ways) and will render bitcoin unusable for the average person  
Switching of the internet
Brute Force attacks on the network to render it slow and unusable  


Could be attacking it by legal means:


Making it illegal to use bitcoin, and tracking users via ISPs, a few show trials and people won't want to use bitcoin again (so TOR could be again an option to circumvent)
shutting down and making peer sites illegal (if they are not already, e.g. mtgox, silkroad)


Great leverage for Bitcoin will eventually come by using it via smartphones and alike, bringing the currency to the street markets. If they find a way to block these trades, they will also hurt bitcoin a lot.