How to check version of bootrom on iPhone 3GS in Windows...

Windows 7 (on windows XP that does not work!)

1. Move your iPhone to recovery mode
2. Open DEVICE MANAGER in Windows 7
3. In USB devices find "Apple Mobile Device USB Driver"
4. Open Properties of this device
5. Open last tab - "Details"
6. Find in "Property" (dropdownlist) value: "Device Instance Path"
7. Check the end of string in "Value"

If you find there "[IBOOT-359.3.2]" - wait for jailbreak... right now it's jailproof...

...if not - use blackra1n.