The iPod touch 2nd Generation features a "thin contoured metal design" reminiscent of the iPhone 3G shape that is slightly thicker (0.02 inch) but lighter than the original iPod touch with a silver front trim rather than gray. Like the original model, the iPod touch 2nd Generation features a "multi-touch" sensitive 3.5" display with 320x480 resolution -- albeit a higher-quality one than that provided by the original -- an accelerometer that allows the device to "know" whether it is being held in portrait or landscape mode and switch automatically, an ambient light sensor to adjust screen brightness, built-in support for Wi-Fi (802.11b/g), and 8, 16, or 32 GB of flash memory.

Compared to the original iPod touch, the second generation model has welcomed external volume controls on the left side of the device, an integrated speaker (external microphone supported via the Apple Earphones with Remote and Mic), built-in support for the Nike + iPod Sport Kit, a "Genius" feature to dynamically create playlists based on "songs that go great together", and shaking the device gently "shuffles" songs.

What are the differences between the iPod touch 3G (Late 2009) and the iPod touch 2G?

Externally, there essentially is no difference between the iPod touch 3G and the iPod touch 2G models that the 3G line replaced. Please note that "3G" stands for "third generation" and, rather confusingly, the iPod touch 3G models do not support 3G mobile networking. In recognition of potential confusion, Apple quietly refers to these models as the "Late 2009" line rather than use the company's traditional "generational" nomenclature.

Both the iPod touch 2G and 3G feature a "multi-touch" sensitive 3.5" display with 320x480 resolution (163 ppi), an accelerometer, an ambient light sensor to adjust screen brightness, built-in support for Wi-Fi (802.11b/g), "shake to shuffle" support, integrated support for Nike + iPod, and flash memory storage (of differing capacity -- 8, 16, or 32 GB for the 2G and 8, 32, or 64 GB for the 3G).

For all practical purposes, in fact, the 8 GB configuration of the iPod touch "3G" series is a re-issue of the 8 GB configuration of the iPod touch 2G that came before it, just sold for US$199 instead of US$229.

Although they are sold as a single line with 8 GB, 32 GB, or 64 GB of storage -- and marketed with greater emphasis on gaming than previous models touted more as an "iPhone without the phone" -- the 32 GB and 64 GB models are significantly different internally from the 8 GB one.

Internally, the 32 GB of 64 GB models have more in common with the iPhone 3GS with advertised "50% faster performance" -- courtesy of the same 800 MHz Samsung ARM processor that powers the iPhone 3GS -- and OpenGL ES 2.0 support for superior graphics performance as well as 256 MB of RAM. The 8 GB model, on the other hand, uses the same 533 MHz Samsung ARM as the iPod touch 2G models and 128 MB of RAM. The 32 GB and 64 GB models also add "Voice Control" navigation capability and a "VoiceOver" screen reader -- the "world’s first gesture-based screen reader" -- but the 8 GB model is not powerful enough to support either feature.