I figured today was the day the invitations go out...I think the future of the iPhone seriously depends on this one. People are starting to realize where the competition is - especially with the windows 8/windows phone 8 coming around the corner. It's a battle of eco systems and innovations.
Google has an advantage here because of maps/gmail/youtube etc - basically the web services king. Not to mention multiple OEM's fueling it's innovations.
Microsoft has the advantage here because it also has multiple OEM's (Nokia being a huge asset), it has a new very connected operating system, and not to mention xbox - the #1 selling console.
Apple really needs to up it's game here. Both Google and Microsoft let you use a lot of their features on multiple platforms which increases adoption rate. Not just that, but they are using a lot of new hardware suppliers this time around thanks to it's recent lawsuits - potential flaws in hardware here. This is also the first iPhone with (hopefully) LTE so hopefully they've done something to work out battery life in a smaller phone. I don't think a 4 inch iPhone will change much aside from adding an extra row of icons. Usability will probably be the same. I do hope the iPhone has NFC. I hate to say it but that's probably the best way to get it spread out. I just hope it's not some crippling proprietary crap...
another interesting way to think about things:
To be in the Apple eco system, you need to spend at least $1200+. $200 iPhone on contract + $1000+ Apple computer.
To be in the Google eco system you need to spend $0.
To be in the Microsoft eco system, you need to spend $0 - $$$ (free phones available, many microsoft services are free and spread out to different platforms)