The NSL comes in a silver and charcoal plastic package that's about the size of a portable standard-sized cassette tape player. Although it has rubber feet on one side, you'll probably want to use the included base and stand it up so that you can better see the status lights. The lights include Ready/Status and Ethernet, Disk 1 and Disk 2 link / activity.
Updated 7/9/2004 The NSL contains a complete embedded computer (Figure 1) based on the Intel IXP420 Network Processor and backed by 8MB of flash and 32MB of RAM. It even has a real-time clock chip and on-board buzzer / beeper!
The single 10/100 Ethernet port is supplied via a Realtek RTL8201 Single-Port 10/100M Fast Ethernet PHYceiver and the dual USB 2.0 ports come courtesy of an NEC D720101 USB 2.0 host controller. The IXP420 comes in 266, 400 and 533 MHz flavors, but I couldn't tell which one is used. An item that the NSL doesn't have is a fan, so it's wonderfully silent in operation.
Figure 1: The NSLU2's board
Linksys' spec says that the NSL supports SMB (Server Message Block) / CIFS (Common Internet File System) over TCP/IP, which most modern operating systems support. Since the NSL is Open Source based, it essentially is a SAMBA server in a cute little box, with a friendlier user interface than you get with most SAMBA implementations. Note that the NSL uses the Ext3 file system, so you can't swap a USB drive between a Windows PC and the NSL without reformatting it - and losing the stored data.
Fans of hacking Linksys' Open Source based WRT54G router [reviewed here] will be happy to know that the company has presented you with another opportunity in the NSL. If you browse the included CD, you'll find a folder that contains original source for the SnapGear Embedded Linux that runs the NSL, plus source files for the various modified Linux modules used in the product.