I just found new Guruplug pages from Wiki. Please look at
http://plugcomputer.org/plugwiki/index.php/Recreating_the_GuruPlug_RFS

In that page it says:

"By default, the RFS boots up within an AP mode with the SSID GuruPlug-4E2F (where 4E2F are the least significant two bytes of the MAC Address). The GuruPlug acts as a wireless router and treats the wired interface as the WAN interface."

 

Another dead Sheevaplug power supply.

My advice,
DO NOT USE ANY EXTERNAL USB DISK with SHEEVAPLUG WITHOUT EXTERNAL POWER!

After a few weeks running with external Lacie Porche 100 GB 2.5" mobile drive with Debian installed to this disk and power from Sheeva USB  I ended up with a dead Sheevaplug. It all happened a couple days ago when I installed more SW and compiled Hiawatha server in the plug. After it my Plug died, and when booting I had the usuals symptoms in this thread. No dmesg in my USB/Serial host and plug had green led and Ethernet leds blinking. I tried to boot with different peripherals plugged/unplugged, but no response in serial connection.  Opened up the plug,  tested the voltage and it was ok, 5.2 V.  But based on the previous posts I took the power supply of and did some soldering and with external power supply my Sheevaplug did boot successfully and now it is running happily with external power for both plug and USB DISK. I am running version 1.3 of the original Sheevaplug.