A few months back, we were still doubtful whether or not Apple was serious about releasing an updated version of their oh-so-popular cell phone. Fast forward to the present- the 3G iPhone has been confirmed with near-100% certainty, and analysts are starting to bet on the exact day the iPhone’s big brother will be born. The latest- and most reliable- prediction is June 9, a Monday. The date comes from Citi analysts Richard Gardner and Yeechang Lee, who coined the day as “D-Day for 3G.”

“We expect a steady stream of new products beginning on June 9th, with a 3G iPhone and iPhone/iPod touch SDK, continuing with a refresh of the complete laptop line in July/August and concluding with a complete refresh of the iPod line in August/September,” Gardner told investors. (June 9th is the date of this year’s Worldwide Developer’s Conference.)

Several other sources are reporting the same: Randall Stephenson (AT&T’s CEO) and Bank of America analysts point to a launch date in early June.