Nobody outside of Apple’s core group of bigwigs and monocle-wearing Monopoly men knows exactly when the 3G iPhone will be released, but Goldman Sachs analyst David Bailey has already been 1 for 1 with his surprisingly accurate prediction that the current generation iPhone will receive a simple size bump in Feburary. The relevance here is that with a strong track record, there may be significant weight to his claim that a new iPhone in the second half of 2008 “[will] have a similar form factor as the current version although it could have a different look and will probably include 3G capability.” That sounds fairly vauge, but he was the first to accuratly predict the update and comes from a reputable ilk, so perhaps there is some basing to his statement.

The June date is simply placed due to its proximity to Apple’s WWDC convention, where they unveiled the shipping date for the original iPhone. Many other sources are claiming a June date, so it is shaping up to be both a fairly reasonable estimate and a very likely outcome.

To summarize, you have about two months to sell your old iPhone on eBay before the 3G version comes rumbling along to kill your resale value.