The appearance, in some online store catalogues, of the dual-core Athlon X2 3800+ processor marks a welcome new entry to the processor battles. Although not yet officially announced, the X2 3800+ is expected to have a clockspeed of 2.0Ghz and to have 2x512Kb level 2 cache. Expect it to retail for around $US350, which is about 60% of the cost of the previous low end Athlon64 X2.
With performance which exceeeds that of comparable Pentium dual-core processors, the Athlon64 X2 series has also been priced more highly. Expect to see some serious competition ahead for the entry level Pentium D 820 and 830 processors.
Dual-core processors, of course, are not the best option for all purposes. Those people who run single threaded applications such as 3D games will get no benefit, as dual-core processors generally offer lower performance in single core applications. Top of the range X2 4800+ for example only matches the single thread performance of the Athlon64 4000+. Those people running applications programs which can take advantage of multithreading, however, have much to smile about.
Edit:
AMD has now confirmed the availability of this entry level dual-core processor