My laptop's wifi stopped working when I upgraded to Ubuntu 12.04 (wired works). I just reinstalled 12.04 over my old 12.04 on which wifi didn't work either in an attempt to restore any settings I may have accidentally changed, but it still doesn't work. I also used a wired connection to install updates in case this bug has been fixed, but it has not. Here is the result of sudo lshw -class network:

  *-network               
   description: Wireless interface
   product: Centrino Wireless-N + WiMAX 6150
   vendor: Intel Corporation
   physical id: 0
   bus info: pci@0000:02:00.0
   logical name: wlan0
   version: 67
   serial: 40:25:c2:5f:5b:f4
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
   configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-29-generic-pae firmware=41.28.5.1 build 33926 latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
   resources: irq:51 memory:de800000-de801fff
  *-network
   description: Ethernet interface
   product: AR8151 v2.0 Gigabit Ethernet
   vendor: Atheros Communications Inc.
   physical id: 0
   bus info: pci@0000:04:00.0
   logical name: eth0
   version: c0
   serial: 14:da:e9:c0:da:78
   capacity: 1Gbit/s
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI firmware=N/A latency=0 link=no multicast=yes port=twisted pair
   resources: irq:54 memory:dd400000-dd43ffff ioport:a000(size=128)

Here is rfkill list all:

0: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
1: asus-wlan: Wireless LAN
Soft blocked: no
Hard blocked: no
2: asus-wimax: WiMAX
Soft blocked: no
Hard blocked: no

lsusb:

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 003: ID 8087:07d6 Intel Corp. 
Bus 001 Device 004: ID 13d3:5710 IMC Networks 
Bus 002 Device 003: ID 045e:0745 Microsoft Corp. Nano Transceiver v1.0 for Bluetooth
Bus 003 Device 003: ID 0781:5530 SanDisk Corp. Cruzer

lspci:

00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM         Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor    Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB   Enhanced Host Controller #2 (rev 05)
00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b5)
00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b5)
00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b5)
00:1c.5 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 6 (rev b5)
00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 05)
00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 05)
00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 05)
02:00.0 Network controller: Intel Corporation Centrino Wireless-N + WiMAX 6150 (rev 67)
03:00.0 USB controller: ASMedia Technology Inc. ASM1042 SuperSpeed USB Host Controller
04:00.0 Ethernet controller: Atheros Communications Inc. AR8151 v2.0 Gigabit Ethernet (rev c0)