Apple's annual developer conference in San Francisco.
iOS 5 Contains References to Two Next-Generation iPad Models
The report does note, however, that these indications of new models do not always lead to new product releases, as a previously-discovered "iPhone3,2" has yet to see the light of day following the release of the GSM (iPhone3,1) and CDMA (iPhone3,3) iPhone 4 models. The missing model may have been destined for a carrier running on a different standard such as T-Mobile's slightly-different GSM 3G network, but a deal with such a carrier may simply have fallen through.
Today's report also cites the presence of "iPhone4,1" and "iPhone4,2" references pointing to the next-generation iPhone. These references are not new, however, as they appeared in iOS 4.3 betas as far back as early January.
Interestingly, iOS 5 currently makes no reference to any unreleased iPod touch models, maxing out at the current "iPod4,1" fourth-generation iPod touch. This of course does not mean that no new iPod touch is in the works, but it is curious that device identifiers for models presumably set for introduction in just a few months are not included.