However since IPSW isn't released for public yet, you're going to need to provide it once to Redsn0w -- but it's going to be one time job, for Redsn0w to cache all the important info, so in the future there is no need to select it again.
And for iPhone 4 and 3gs owner who still have their basband and using Mac, your OS can produce the NO_BB *custom IPSWs for 5.0.1. And for the unlocker, it's not recommended to update to iOS 5.0.1 b 2, because you will lose unlock ability.
Remember the jailbreak is tethered which means you're going to need to jailbreak your device each time rebooting and it can't be used to jailbreak iPhone 4s and iPad 2.
Since everything is cleared, now let's jailbreak iOS 5.0.1 beta 2 with Redsn0w 0.9.9b8
1. Download the iTunes v 10.5 for Mac here and or for Windows here and for Windows 64 bit here.
2. Connect your iOs device to your computer (Mac or Windows). And firstly backup your important data, in case the unexpected things happens, you have backup!
3. Download 5.0.1 Beta2 based on your Operating Systems, you can Google it or simply visit Apple Dev site if you have account.
4. Download Redsn0w 0.9.9b8, again based on your OS: visit here for Mac users and here for Windows users.
5. Open Redsn0w, and then click on Extras, after that click on Select IPSW. And you will be taken to the final public iOS 5 firmware that matches your iOSdevice.
6. Select “Jailbreak” option, continue the process by installing “Cydia”. And DFU mode your iOS Device to make Redsn0w start jailbreaking it.
7. After jailbreaking process is completed, your iOs device will reboot itself, and Cydia can be used. If that's so, open redsn0w again and tab on Extras followed by Just boot to boot the tethered firmware. Done, now you get your iOS device running on iOS 5.0.1 Beta 2 is jailbroken!