You Can Now Easily Jailbreak Your iphone 4 Running IOS 4.1 Using  Limera1n Once You Finish Jailbreak For Your iphone 4 can be customized  in many ways. However, more importantly you have the  ability to add  features via apps that
Apple doesn’t endorse. You won’t see these  apps in  the regular iTunes App Store on your iPhone  4. Instead you’ll have to  download or purchase these apps like Frash,  an app that puts Adobe’s  Flash player on your iPhone 4, from the Cydia  store instead.
Today i am Going To Show You How To Add Flash Playback To Your iphone 4   in Three Easy Steps By Using An App Called "Frash" By @Comex  
First Step: is To Launch Cydia App On Your iphone 4  And Tap Manage
Step 2 :Add the Source for the Frash app by tapping Sources, Edit, and Add. A dialog opens reading 
Enter Cydia/APT URL immediately following the provided “http://” enter 
repo.benm.at and tap Add Source. Once this is completed tap Return to Cydia
And Last Step 3 : Install Frash by tapping Search and enter 
Frash as the search criteria. Tap 
Frash – Flash for iOS   then tap Install and then Confirm. Frash will begin to install taking   only a few minutes or less. Once it is completed tap Return to Cydia.

Frash is now installed on your iPhone 4 and ready to go. Launch  Safari  and navigate to http://www.adobe.com to try it out. Initially  you’ll  see a gray place holder labeled 
Flash for the flash content on a web page. If you tap it you’ll see the flash content start to play.

The content that I tested and experimented with was either hit or  miss  as far as the results went during testing. It worked some of the  time  and often did not work at all or crashed, but it is still some what   useful for Flash games and videos.

Normally, there is an option called Frash Toggle for SBSettings which   is an app that will allow you to toggle Frash on and off. I usually   recommend installing that app also, but the currently available version   only works on iOS 3.2. You’ll see a warning from Cydia about this prior   to installing it. Hopefully the author will find some time to update  the  app to iOS 4.1 so you could install it yourself later. I skipped it  for  the time being with the hope of keeping the jailbroken iPhone 4  stable.