Google's network will be fiber optical cable having the ability to transmit 1 Gigabit per second, that is 1,000 Mbps.

Here's what that means compared to other services:

Type Download Upload
DSL Tier 1 384kbps - 1.5Mbps 128kbps - 384kpbs
DSL Tier 2 1.5Mpbs - 3.0Mbps 384kbps- 512kpbs
DSL Tier 3 1.5Mpbs - 6.0Mbps 384kbps - 608kpbs
Cable Starter 6Mpbs 1Mpbs
Cable Premium 5Mpbs 50Mpbs
Cable Deluxe 50Mpbs 10Mpbs

key:

kbps = kilo bits per second
Mpbs = Megabits per second

1,000 kpbs = 1 Mbps

Sources: Comcast web site and PON.net (jobber for AT&T)