Lately there have been quite a lot of so-called "unsolicited redesigns" posted all over the web and I do applaud the effort, don't get me wrong. I just can't help but wonder why you would want to take a shot at Microsoft, Facebook or even Apple's new iOS interface.
These concepts really do look superb and you can tell a lot of hours have gone into those projects. However, there is only one tiny detail that leaves me skeptical about this approach: the final product is already out there and set in stone. So unless you work at said companies, chances are pretty slim that your design would actually get noticed, much less have an impact on how people use the product. At least I tend to think that's what it's all about in the end: having a positive impact on your users. Making life easier and more enjoyable.
Granted, if you are lucky and the right people notice, you just might turn that concept of yours into reality. I mean it worked out alright for Andrew Kim after all.
I guess it's worth a shot, but why not try to fix things that are in dire need of fixing instead? Think of products you use on a daily basis that leave you really frustrated because of poor design decisions. Pick it apart, figure out what could be improved and get to work.
Now please excuse me while I finish up my redesign of twitter.