Yes it's the day you can finally get your hands on iOS 4. No as of now (2PM GMT) it's not yet available, and no I'm not going to run through every little feature - you can find them here and here. Instead I will tell you some initial observations having used it for the last week.
As I mentioned in podcast 4, it's fast really, really fast - on the iPhone 3GS at least. Taking a photo is almost instantaneous, menu transitions are substantially quicker and scrolling is smoother. iOS 4 is the first firmware update I can remember where handset performance improves on the back of it and that's extremely welcome.
The big news is multi-tasking, but there's a major caveat here: apps need to be updated to work with it, they won't be compatible automatically. Consequently for the majority of apps right now multi-tasking is simply a glorified shortcut to quickly accessing apps and making them reload. This should improve over time and one of the most crucial TuneIn Radio added multi-tasking support today.
Elsewhere numerous apps have glitches or incompatibilities with iOS 4 with crashes and performance hits the main issue. More than any other firmware I can remember, app makers really need to get coding to get the best out of this update.
On the whole though, it is a hugely welcome release with unified inboxes, threaded messages, folder support and battery life holds up (watch out for quirks sending mail from third party apps if you use Google Sync). It is also sure to only get better as app developers find creative ways to take advantage of multi-tasking and features like 'Game Center' come online.
In related news Microsoft has finally released an official Microsoft Live Messenger app for the iPhone. Amusingly multi-tasking support is a little iffy, but it's otherwise slick, fast and free.
In yet more related news O2 has decided to further enhance its rep as the most infuriating network in the UK by announcing only existing customers (mobile, mobile broadband, home broadband or home phone) will be able to buy the iPhone 4 from launch. O2 says this is due to stock shortage, but with the majority of existing customers stuck on iPhone 3GS 18 month contracts it seems somewhat self defeating. On the plus side O2 and Orange have announced free microSIM to SIM adapters will be available so can use your micro SIM in another handset. Handy.
Finally BGR reports some of those who pre-ordered an iPhone 4 direct from Apple have received shipping notices. Whether these are in error or whether handsets may indeed arrive early is unknown, but keep your fingers crossed.
Update 6.30PM GMT: It's live!
Windows Live Messenger (iTunes link)
iPhone 4 Pre-orders Shipping via BGR