[Droid Eris Android Development] MongooseHelix:
So I decided to take a look at your log without much hope that I'd figure much out but here's what I've gleaned from it. I'll start from where Navigation is launched and include items that I thought were important with some comments that hopefully aren't too off-base:

I/ActivityManager( 136): Starting: Intent { act=android.intent.action.VIEW dat=google.navigation:///?fd=true cmp=com.google.android.apps.maps/com.google.android.maps.driveabout.app.NavigationActivity } from pid 3578
...
V/NavigationService( 3578): onStartInternal. Intent: Intent { act=android.intent.action.VIEW dat=google.navigation:///?fd=true cmp=com.google.android.apps.maps/com.google.android.maps.driveabout.app.NavigationService }
...
#A surface for Navigation to use for graphics
V/RenderThread( 3578): Surface created
V/RenderThread( 3578): Surface changed: 320, 403
...
#Gralloc allocates memory for the graphics
D/gralloc ( 136): allocating GPU size=258048, offset=0
D/gralloc ( 136): allocating GPU size=258048, offset=258048
...
#Renderer error that will continue to repeat often(won't include any other instances of it in this post though)
E/Renderer( 3578): drawFrameInternal GL ERROR: 1280
...
#Service for network location dies and then gets started back up
I/ActivityManager( 136): Process com.google.android.apps.maps:NetworkLocationService (pid 2657) has died.
W/ActivityManager( 136): Scheduling restart of crashed service com.google.android.apps.maps/com.google.android.location.internal.server.NetworkLocationService in 5000ms
I/ActivityManager( 136): Start proc com.google.android.apps.maps:NetworkLocationService for service com.google.android.apps.maps/com.google.android.location.internal.server.NetworkLocationService: pid=4324 uid=10077 gids={3003, 1015}
...
#DoggCatcher, a podcast app being used, encounters an unexpected socket timeout exception here when attempting to fetch a feed
...
#DoggCatcher encounters another unexpected socket timeout exception here when attempting to fetch a feed
...
#The system_server process produces(or reacts to?) an invalid memory reference(segfault)
I/DEBUG ( 90): pid: 136, tid: 5473 >>> system_server <<<
I/DEBUG ( 90): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 00000000
#The debugger then prints out the contents of registers, pc(program counter), code around pc, code around lr(return address), and the stack
...
I/Process ( 136): Sending signal. PID: 136 SIG: 3 #SIGNAL_QUIT
I/dalvikvm( 136): threadid=4: reacting to signal 3

#Repeats "Signal Catcher" lines until after spin on suspend #10
W/dalvikvm( 136): threadid=4: spin on suspend #1 threadid=49 (pcf=0)
W/dalvikvm( 136): threadid=4: spin on suspend #2 threadid=49 (pcf=0)
I/dalvikvm( 136): "Signal Catcher" daemon prio=5 tid=4 RUNNABLE
I/dalvikvm( 136): | group="system" sCount=0 dsCount=0 obj=0x4050d348 self=0x8f1a0
I/dalvikvm( 136): | sysTid=139 nice=0 sched=0/0 cgrp=[no-cpu-subsys] handle=986328
I/dalvikvm( 136): | schedstat=( 106689453 320892336 320 )
I/dalvikvm( 136): at dalvik.system.NativeStart.run(Native Method)
I/dalvikvm( 136): "(null)" prio=0 tid=49 RUNNABLE
I/dalvikvm( 136): | group="(null; initializing?)" sCount=1 dsCount=0 obj=0x408f2468 self=0x3be5d8
I/dalvikvm( 136): | sysTid=5473 nice=0 sched=0/0 cgrp=[no-cpu-subsys] handle=1969736
I/dalvikvm( 136): | schedstat=( 2258300 55053713 8 )
I/dalvikvm( 136): at java.lang.Thread.<init>(Thread.java:~387)
I/dalvikvm( 136): at dalvik.system.NativeStart.run(Native Method)
W/dalvikvm( 136): threadid=4: spin on suspend #3 threadid=49 (pcf=0)
...
E/dalvikvm( 136): Fatal spin-on-suspend, dumping threads
I/dalvikvm( 136): DALVIK THREADS:
I/dalvikvm( 136): (mutexes: tll=2 tsl=1 tscl=0 ghl=0 hwl=0 hwll=0)
#Appears to check every dalvik thread(tid=#) trying to lock mutexes? (waiting to lock...)
...
E/dalvikvm( 136): threadid=4: stuck on threadid=49, giving up
D/dalvikvm( 136): threadid=4: sending two SIGSTKFLTs to threadid=49 (tid=5473) to cause debuggerd dump #Stack Fault
D/dalvikvm( 136): Sent, pausing to let debuggerd run
D/dalvikvm( 136): Continuing
E/dalvikvm( 136): VM aborting
...
#Services and processes die
...
I/DEBUG ( 90): debuggerd committing suicide to free the zombie!
D/Zygote ( 92): Process 136 terminated by signal (11) #SIGSEGV
I/Zygote ( 92): Exit zygote because system server (136) has terminated
#More stuff dies
##REBOOT##

The reboot looks to originate all the way back with allocating memory for navigation graphics which triggers the first of many renderer errors. This leads to a segfault which the system cannot recover from and causes a reboot. I did find that people with other phones have experienced this issue as well. Some links: Desire with Oxygen(AOSP), Hero with CyanogenMod, and another Desire thread. The renderer error shows up in all of the cases so something is going wrong with either the allocation or usage of graphics memory where eventually you get a segfault. Someone smarter than me will be needed :).