Figure 3 is a shot of the 655 with its top cover removed. All of the interesting stuff is tucked under the RF shield to the right of the photo, which didn't come off easily so I left it in place. A bit of Googling, however, revealed the processor to be the Ubicom StreamEngine 5160. The switch is, of course 10/100/1000 and provided by a Vitesse VSC7385. The design also has 16 MB of RAM but I couldn't find the amount of Flash used.
Figure 4: Main board top
The mini-PCI radio module to the left is an Atheros AR5BMB71 reference design based on one of the xSpan AR5008 series chipsets. Unfortunately, the FCC photo in Figure 5 doesn't provide enough detail to tell which one.
Update 11/26/2007: This X-bit labs review identifies the Atheros chips used in the DIR-655 and DWA-652 as the AR5416 Baseband / MAC and AR2133 3T3R 2.4 GHz radio.
Figure 5: Router mini-PCI radio module
Figure 6 shows the board of the 655's companion DWA-652 Notebook Adapter. You can make out the AR5416 MAC/Baseband chip, but, unfortunately again, not the radio chip.