The only data I'd rely on to infer geo-location is hop name and latency. Consider:
11/19/08 01:43:17 Slow traceroute 72.134.32.40
Trace 72.134.32.40 ...
192.168.0.1 RTT: 0ms TTL:170 (suzuka.aosake.net ok)
69.105.225.254 RTT: 10ms TTL:170 (adsl-69-105-225-254.dsl.pltn13.pacbell.net ok)
64.164.107.130 RTT: 9ms TTL:170 (No rDNS)
151.164.93.231 RTT: 9ms TTL:170 (bb1-g15-0.pltnca.sbcglobal.net ok)
151.164.191.201 RTT: 9ms TTL:170 (ex1-p9-0.eqsjca.sbcglobal.net ok)
151.164.249.78 RTT: 10ms TTL:170 (No rDNS)
66.109.6.136 RTT: 10ms TTL:170 (No rDNS)
66.109.6.7 RTT: 19ms TTL:170 (ae-4-0.cr0.lax00.tbone.rr.com probable bogus rDNS: No DNS)
66.109.6.103 RTT: 19ms TTL:170 (No rDNS)
66.75.161.48 RTT: 22ms TTL:170 (ae10.tustca1-rtr1.socal.rr.com ok)
66.75.145.12 RTT: 26ms TTL:170 (xe-0-0-0.chswca1-rtr2.socal.rr.com ok)
66.75.145.29 RTT: 46ms TTL:170 (ae5-resdca1-rtr2.socal.rr.com ok)
24.24.193.149 RTT: 50ms TTL:170 (No rDNS)
* * * failed
* * * failed
* * * failed
* * * failed
* 24.24.193.149 RTT: 44ms TTL:170 (No rDNS)
* * * failed
* * * failed
This trace is entirely inside of California. First hop is the D-Link DIR-655 sitting on the printer stand beside my computer desk. Then a DSL aggregation router in Pleasanton, California (ATTIS is DSL to the DSLAM and ATM to the aggregation router, so no intermediary IP hops between my router and their first router). Past the no-name router at [66.109.6.103] I am going through many of the same hops to your IP address.
Both 'pacbell.net' and 'sbcglobal.net' are part of the AT&T Internet Services (ATTIS) transit network; somewhat similar to Road Runner's 'tbone' network.
Anyway, 'pltnca', 'sjca', 'irvnca', 'lax', 'tustca', 'chswca', and 'resdca' all appear to match city names in either the S.F. Bay Area, or L.A. Metro.