[Sony Tablet S] jappaj:
Wait what... I just found out, that when I am in recovery console, my computer sees SGPT121 device but does not have driver for it. When device worked, I had drivers. I used "Sony Tablet ADB Driver Automated Installer" to install drivers and when I explored android_winusb.inf I found out that this automated installer installed drivers only for composite adbdev interface, not for single adb interface. So I manually added correct pids etc. and was then able to install drivers and now I can actually see my device booted to recovery:

List of devices attached

0123456789ABCDEF recovery

Shell wont work however as expected so probably still impossible to unbrick, but at least I was able to pull recovery.log:

Starting recovery on Sun Apr 21 10:29:00 2013

can't open /dev/tty0: No such file or directory

framebuffer: fd 3 (1280 x 800)

recovery filesystem table

=========================

0 /tmp ramdisk (null) (null) 0

1 /hwconfigs ext2 /dev/block/mmcblk0p1 (null) 0

2 /configs ext4 /dev/block/mmcblk0p2 (null) 0

3 /system0 ext4 /dev/block/mmcblk0p3 (null) 0

4 /system1 ext4 /dev/block/mmcblk0p4 (null) 0

5 /cache ext4 /dev/block/mmcblk0p5 (null) 0

6 /misc emmc /dev/block/mmcblk0p6 (null) 0

7 /staging ext4 /dev/block/mmcblk0p7 (null) 0

8 /blflags ext4 /dev/block/mmcblk0p8 (null) 0

9 /datapp ext4 /dev/block/mmcblk0p9 (null) 0

10 /log ext4 /dev/block/mmcblk0p10 (null) 0

11 /data ext4 /dev/block/mmcblk0p11 (null) -32768

12 /sdcard vfat /dev/block/mmcblk1p1 /dev/block/mmcblk1 0

13 /boot emmc boot (null) 0

14 /recovery emmc recovery (null) 0

15 /system ext4 system (null) 0

16 /vendor0 ext4 vendor0.img (null) 0

17 /vendor1 ext4 vendor1.img (null) 0

Command: "/sbin/recovery"

ro.secure=1

ro.allow.mock.location=0

ro.debuggable=0

persist.sys.usb.config=mtp

ro.build.id=TID0142

ro.build.display.id=TID0142

ro.build.version.incremental=121116001

ro.build.version.sdk=15

ro.build.version.codename=REL

ro.build.version.release=4.0.3

ro.build.date=Fri Nov 16 01:16:55 JST 2012

ro.build.date.utc=1352996215

ro.build.type=user

ro.build.user=integ-build

ro.build.host=build8

ro.build.tags=test-keys

ro.product.model=SGPT12

ro.product.brand=Sony

ro.product.name=SYS_052

ro.product.device=txs03

ro.product.board=txs03

ro.product.cpu.abi=armeabi-v7a

ro.product.cpu.abi2=armeabi

ro.product.manufacturer=Sony

ro.product.locale.language=en

ro.product.locale.region=US

ro.wifi.channels=

ro.board.platform=tegra

ro.build.product=txs03

ro.build.description=SYS_052-user 4.0.3 TID0142 121116001 test-keys

ro.build.fingerprint=Sony/SYS_052/txs03:4.0.3/TID0142/121116001:user/test-keys

ro.build.characteristics=tablet

ro.opengles.version=131072

wifi.interface=wlan0

wifi.wpa_supp_ready=0

persist.tegra.nvmmlite=1

windowsmgr.max_events_per_sec=135

ro.tether.denied=true

ro.sony.sound.enabled=true

ro.sony.display.release=release6b

ro.product-res-path=vendor/framework/SemcGenericUxpRes.apk

ro.sony.autovolume.threshold=10

ro.sony.update.server=info.update.sony.net

ro.sony.update.category_id=ST001

ro.config.alarm_alert=Alarm.ogg

ro.config.notification_sound=Notification.ogg

ro.config.ringtone=Ringtone_XPERIA.ogg

drm.service.enabled=true

dalvik.vm.heapstartsize=5m

dalvik.vm.heapgrowthlimit=48m

dalvik.vm.heapsize=256m

ro.sony.wifisleep=0

ro.semc.enhance.supported=true

ro.semc.clearaudio.supported=true

ro.somc.dmnorm.supported=true

ro.setupwizard.mode=DISABLED

ro.com.google.gmsversion=4.0_r6

ro.com.google.clientidbase=android-sony

dalvik.vm.dexopt-flags=m=y

net.bt.name=Android

net.change=net.bt.name

dalvik.vm.stack-trace-file=/data/anr/traces.txt

tf.enable=y

ro.sony.wan.ipv6.enable=false

persist.sys.sony.cabc.disable=0

persist.sys.sony.hdmi.disable=0

ro.sony.dlna_dms.enabled=false

ro.somc.social_product_model=PRODUCT_MODEL_TABLET

ro.sony.irremote.protocol_type=2

ro.sony.ols.eula=1

ro.pss.ps1content_disable=1

ro.factorytest=0

ro.bootmode=unknown

ro.baseband=unknown

ro.carrier=unknown

ro.bootloader=0x00000006

ro.hardware=txs03

ro.revision=0

init.svc.recovery=running

init.svc.nfx_daemon=running

init.svc.radbd=running