[Sony Xperia S, Acro S, Ion] v0ids0ul:
Not quite sure how to do anything with it, but I was poking around /system/etc/wifi/hostapd.conf and found settings for 5ghz. The problem is theydont appear to be set. Maybe someone else can step in and figure it out?

EDIT

I was browsing the net and found a way to check the hardware support for 5Ghz wifi...issuing the command "iw list" while in adb shell outputs the following:

[hide]
Wiphy phy0
Band 1:
Capabilities: 0x1820
HT20
Static SM Power Save
RX HT20 SGI
No RX STBC
Max AMSDU length: 7935 bytes
DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 16 usec (0x07)
HT RX MCS rate indexes supported:
HT TX MCS rate indexes are undefined
Frequencies:
* 2412 MHz [1] (20.0 dBm)
* 2417 MHz [2] (20.0 dBm)
* 2422 MHz [3] (20.0 dBm)
* 2427 MHz [4] (20.0 dBm)
* 2432 MHz [5] (20.0 dBm)
* 2437 MHz [6] (20.0 dBm)
* 2442 MHz [7] (20.0 dBm)
* 2447 MHz [8] (20.0 dBm)
* 2452 MHz [9] (20.0 dBm)
* 2457 MHz [10] (20.0 dBm)
* 2462 MHz [11] (20.0 dBm)
* 2467 MHz [12] (20.0 dBm) (passive scanning, no IBSS)
* 2472 MHz [13] (20.0 dBm) (passive scanning, no IBSS)
* 2484 MHz [14] (20.0 dBm) (passive scanning, no IBSS)
Bitrates (non-HT):
* 1.0 Mbps
* 2.0 Mbps (short preamble supported)
* 5.5 Mbps (short preamble supported)
* 11.0 Mbps (short preamble supported)
* 6.0 Mbps
* 9.0 Mbps
* 12.0 Mbps
* 18.0 Mbps
* 24.0 Mbps
* 36.0 Mbps
* 48.0 Mbps
* 54.0 Mbps
Band 2:
Frequencies:
* 5170 MHz [34] (20.0 dBm)
* 5180 MHz [36] (20.0 dBm)
* 5190 MHz [38] (20.0 dBm)
* 5200 MHz [40] (20.0 dBm)
* 5210 MHz [42] (20.0 dBm)
* 5220 MHz [44] (20.0 dBm)
* 5230 MHz [46] (20.0 dBm)
* 5240 MHz [48] (20.0 dBm)
* 5260 MHz [52] (20.0 dBm)
* 5280 MHz [56] (20.0 dBm)
* 5300 MHz [60] (20.0 dBm)
* 5320 MHz [64] (20.0 dBm)
* 5500 MHz [100] (20.0 dBm)
* 5520 MHz [104] (20.0 dBm)
* 5540 MHz [108] (20.0 dBm)
* 5560 MHz [112] (20.0 dBm)
* 5580 MHz [116] (20.0 dBm)
* 5600 MHz [120] (20.0 dBm)
* 5620 MHz [124] (20.0 dBm)
* 5640 MHz [128] (20.0 dBm)
* 5660 MHz [132] (20.0 dBm)
* 5680 MHz [136] (20.0 dBm)
* 5700 MHz [140] (20.0 dBm)
* 5745 MHz [149] (20.0 dBm)
* 5765 MHz [153] (20.0 dBm)
* 5785 MHz [157] (20.0 dBm)
* 5805 MHz [161] (20.0 dBm)
* 5825 MHz [165] (20.0 dBm)
Bitrates (non-HT):
* 6.0 Mbps
* 9.0 Mbps
* 12.0 Mbps
* 18.0 Mbps
* 24.0 Mbps
* 36.0 Mbps
* 48.0 Mbps
* 54.0 Mbps
max # scan SSIDs: 10
max scan IEs length: 2048 bytes
Coverage class: 0 (up to 0m)
Supported Ciphers:
* WEP40 (00-0f-ac:1)
* WEP104 (00-0f-ac:5)
* TKIP (00-0f-ac:2)
* CCMP (00-0f-ac:4)
* CMAC (00-0f-ac:6)
* 00-0f-ac:7
Available Antennas: TX 0 RX 0
Supported interface modes:
* IBSS
* managed
* AP
* monitor
* P2P-client
* P2P-GO
software interface modes (can always be added):
interface combinations are not supported
Supported commands:
* new_interface
* set_interface
* new_key
* start_ap
* set_bss
* join_ibss
* set_pmksa
* del_pmksa
* flush_pmksa
* frame
* set_wiphy_netns
* set_channel
* connect
* disconnect
Supported TX frame types:
* IBSS: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* managed: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* P2P-client: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* P2P-GO: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
Supported RX frame types:
* IBSS: 0xd0
* managed: 0x40 0xd0
* AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
* AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
* P2P-client: 0x40 0xd0
* P2P-GO: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
[/hide]

So as you can see the hardware support is there.... We do have 5Ghz. I'm going to spend a little time later and try to figure out how to enable it, but if anyone who knows happens to be watching this thread, I and I'm sure the OP along with many otheres would love to know how to do this.