You can save your blobs for any version that Apple is currently signing (which is 4.3.5 now ... maybe 4.3.4, but I think that window is almost closed).
You do NOT have to be on the version for which you want to save blobs. REPEAT: You can save any blob that Apple is signing - but you don't have to have that version installed on your iPad!
Just download/run Tiny Umbrella and start saving blobs. It's good practice.
And, to end this on a downer: I really wouldn't expect a jailbreak to come out for 4.3.5 (or 4.3.4, for that matter) for the iPad2. They were incremental changes to stop the security leak that enabled the jail break for 4.3.3. IMNSHO, I think the jail break community is more focused on the upcoming iOS 5.
However, it's still a good practice to save any blobs you can anyway, even if you don't jail break (as in, don't burn a bridge...). 'Cause you never know...
Marilyn