Guys, let's all just step back and start over - first, that WAS a smart-ass comment, and it WAS intentional - When I read a comment that says "works great", it tells me SQUAT. So my comment "for what", was a smart-ass way of saying, "finish presenting your point - your statement is misleading, for one thing..."
By that, I mean that yes, gobo's work great (for SOME isolation between instruments, NOT for sound proofing one area from another)
Please keep in mind that we have ALL levels of expertise/knowledge coming here, some to help, some to learn, most for BOTH. Incomplete thoughts can (and DO) confuse or corrupt the knowledge being sought, and can lead to a person with $50 to spend, flushing that money down the toilet based on false or incomplete information.
My main reason for the (partially) smart-ass comment was to get Casenpoint to FINISH his statement so no one was confused by (apparently) conflicting statements.
Now that THAT is (hopefully) cleared up, here's what I intended to say (thought I DID say it, guess not) -
If you're on a tight budget, (and I'm talking having to choose between having enough undershorts and saving for a guitar cable) then it's NOT practical to think about a separate control room, tracking room, iso booths, machine room, etc - leave those til you cash in that winning Powerball ticket, or at least have enough income so you can cover your ass AND make cool sounds... Under those conditions, I would recommend recording with the idea that these songs will be "scratch pads" - in other words, save the ideas on whatever media you have, until you can get them recorded in better acoustic space (even if it's a friend's barn, out in the country, whatever) - one way of doing this is as much "direct" recording as possible, ie: no microphones, therefore no acoustic problems (but also no acoustic "sweetness") - Anyway, this post would get even more ridiculously long if I were to go into all that's involved there, check the Newbies area and all the other gear forums for that type of info.
If you're just a little better off than the "no shorts" guy, a good set of closed-ear, non-hyped headphones in a single, (not "chopped up" ) room is a decent work-around - it's kind of a PITA to have to check drum mics, etc, with headphones on in order to keep from hearing too much of the direct sound, but the ALTERNATIVE is pretty expensive.
Gobo's will NOT get you there for full isolation. Moving blankets, drapes, egg cartons, foam, mattresses, piles of dried dog shit, NOTHING will give you near complete isolation between two areas other than properly designed walls. This isn't me being an "elitist", it's just physics. Therefore, to GET this needed isolation you either pay $50 to $100 for a decent set of closed ear headphones, or you spend the time, money, effort, etc, to build (or have built) proper sound proof walls.
The only OTHER way I know of to get that good isolation is if you can transmit your sound a long enough distance without loss so that you can use that friend's barn for a tracking room (hoping the neighbors don't have a retarded dog that barks just to hear his head rattle) and use your apartment 6 miles away for a control room. This is actually becoming more feasible with digital technology, but it's not as cheap as a good set of headphones yet...
One reason FEW of my posts are short is that it isn't possible to ACCURATELY convey anything other than a yes or no with few words. "works great" means anything (or nothing) you want it to mean. "yup" means "I agree with what you said" -
So, when I say something like, " for what?" - It means, "wake up - you didn't explain yourself well enough to avoid confusion" -
Hopefully this will clear up my intent, which is to (mostly) minimise confusion... Steve
No wonder I sit lopsided. 
