A little impatient... Save this as a .vbs file and use it. I haven't tested it, so I'd try it only on one first. I'm not trying to blow up your computer or anything, but if anything happens, I'm not liable.
On Error Resume Next
strAnswer = MsgBox("This will format all flash drives attached to your computer. Continue?", 4 + 48, "Format all flash drives")
If strAnswer = vbNo Then WScript.Quit
strComputer = "." 'Your computer
Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2") 'Make WMI connection
Set colDisks = objWMIService.ExecQuery("Select * from Win32_LogicalDisk") 'Enumerate all disks
For Each objDisk in colDisks 'For each of those disks...
strDrive = objDisk.DeviceID 'Get the drive's letter (ex: E:, F:, etc.)
strType = objDisk.DriveType 'Get the drive's type (We're looking for "Removable Disk")
Set colVolumes = objWMIService.ExecQuery("Select * from Win32_Volume Where Name = '" & strDrive & "\\'")
If strType = 2 Then 'If the drive is a removable disk (flash drive)...
For Each objVolume in colVolumes
objVolume.Format("FAT32") 'Format it using the FAT32 filesystem
Next
End If
Next