Yes, you're most ilikely correct.
Apple like to keep their releases quiet until the day of release. Around June/July time each year, there is a conference and expo called WWDC in California, where people developing apps for the Mac and iPhone systems get to talk to Apple devs, learning new skills.
It's traditionally a time for Apple to announce new systems. For the past two years running, new iPhones have been released this time of year. Currently, it seems that this year will be no different. But since Apple is secretive, all you can do is speculate until they're actually unveiled. I think that the new iPhone will have:
- Better camera, probably autofocus lens, and capable of video (with software coming as part of iPhone 3.0).
- 'Digital compass', useful for satnav-type apps and perhaps games.
- Matte black back, perhaps with black rim (no longer chrome).
- Faster processor, ideal for gaming. Probably more RAM, and larger storage capacities offered.
- A few different versions of the phone, with at least one being capable of faster 3G speeds (~ 7.2Mbps, so-called '3.5G' technologies).
Note that new software will also be released at the same time, called iPhone 3.0 (currently it's 2.x). This will be compatible with the current iPhone 3G and the original iPhone, will be free for iPhone 3G owners, and a small fee for iPhone original owners (due to an accounting law in the States). This will provide copy and paste, MMS messaging, and a host of other features that are nice additions to the current software.