AMD to start Bulldozer AM3+ production by March 2011, launch in April 2011

[kl0012]

Actually hyper-threading was criticized for being energy-inefficient.For example, ARM has stated SMT can use up to 46% more power than dual core designs.

Adding performance feature will add some power consumption. This is natural. I can't comment ARM design, but SB is very efficient even with HT.

Furthermore, they claim SMT increases cache thrashing by 42%, whereas dual core results in a 37% decrease.

Cache trashing is mostly function of cache size and quality of software. In fact Bulldoser will be affected in the same way as SB with HT since each module uses shared cache (while dedicated L1 was reduced to just 16k).

Not to mention that in May 2005 Colin Percival demonstrated that a malicious thread operating with limited privileges can monitor the execution of another thread through their influence on a shared data cache, allowing for the theft of cryptographic keys.

Hyperthreading is largely a strong negative effect to any system.

Well... This is funny. In fact, no absolutely secure hardware exists. There was introduced Blue Pill malware which uses security holes in AMD virtualization technology. Can we say AMD-V is a "strong negative effect" to any system?

Update:
Since you used wikipedia as your source of information, I just want to add a sentence which you forgot to copy:

In May 2005 Colin Percival demonstrated that a malicious thread operating with limited privileges can monitor the execution of another thread through their influence on a shared data cache, allowing for the theft of cryptographic keys.[15] Note that while the attack described in the paper was demonstrated on an Intel Pentium 4 processor with HTT, the same techniques could theoretically apply to any system where caches are shared between two or more non-mutually-trusted execution threads; see also side channel attack.

Also:
In 2010, ARM has stated that it will include simultaneous multithreading in its chips in the future.