It's been over a week since the iPhone 4 was launched, then rapidly disappeared off the shelves. Well, stock just might be starting to reappear again, albeit very slowly.O2 is the first network to promise new stock, advertising the fact via its Twitter account. According to O2 on Twitter: 'We’ve got more iPhone 4 stock going into our stores this wkend. Supplies are very limited so see stock.o2.co.uk for details from 12pm Friday'.Which pretty much sums it up. Get on that website this lunchtime for details of where to find an iPhone 4 this weekend and beyond, whilst stocks last that is. You might even be able to order one online, website stability permitting. No news on numbers, but we're guessing it isn't a huge amount.As for the rest? Well, Tesco is still saying the end of July, Vodafone is employing a 'first come, first served' allocation to anyone who happens to order one online with them and Orange has talked about more stock, but has yet to confirm.Of course, we've still not seen the entry into the market of either the Three network or T-Mobile. The first of those has announced it will be offering the iPhone 4 from the end of July with a favourable contract, while T-Mobile still trots out the 'coming soon' mantra, which it has been reciting since the launch day. Will it ever arrive on the network? Who knows.