Actually it's a 350MHz ARM9 and 64MB SDRAM:

350MHz Freescale iMX21 MC94MX21DVKN3 ARM9 controller Datasheet Technical Information
Samsung 64MB SDRAM on 32-bit data path
Hynix HY27US 64MB NAND Flash ROM
Three USB 2.0 full speed ports, one internal, two external
Xterasys 3135G 802.11g USB Wifi adapter (ralink chipset)
DataImage 320hx240v 16bpp TFT display with touchscreen
Texas Instruments TSC2100 Programmable Touchscreen Controller with Stereo DAC Datasheet
2W stereo speakers, with headphone jack
Built-in microphone
"Bend" switch
Kionix KXP74-1050 3-axis accelerometer Datasheet Specifications
STMicroelectronics STR711FR0/1 ARM7 "crypto" processor Datasheet
Soft-switch on power, controlled by crypto processor
TTL serial port @38400 8N1

Chumby is possibly a bit more hackable. The slim devices stuff does have some level of customisability though.