Looks like the iPhone 4S is actually going to launch in September as previously stated. Digitimes reports that Apple has slowed production on the current iPhone 4 in preparation for iPhone 4S production and is scheduled to launch as early as September.
Apple has lowered its expected shipment volume of iPhone 4 for the second quarter of 2011 from 20 million units, to 17.5-18 million units consisting of 16 million units of the 3G version and 1.5-2 million units of the CDMA version, according to Taiwan-based supply chain makers.
It is also indicated that the iPhone 4S camera will be upgraded to an 8 megapixel version which will be provided by Omnivision. In a report by 9to5Mac, the new iPhone may include support for both the T-Mobile and Sprint networks but will not have LTE support as also mentioned on this site. However the phone may support AT&T HSPA+ network. LTE support for the iPhone may come in the next version in 2012 which seems most likely.