If one assumes — as many were on Tuesday — that Apple (AAPL) puts as much thought into the iconography of its invitations as it does into the icons on its computer screens, there are several conclusions one could draw from the “Let’s talk iPhone” e-mail sent to selected member of the media.

The meaning of first three icons is pretty clear: Apple is holding an event at 10 a.m. Oct. 4 at its corporate headquarters, and if you’re driving from San Francisco, 280 is the route to take. (If there were any doubt about this, the text of the invitation says as much.)

But there’s more. Piper Jaffray’s Gene Munster takes the “let’s talk” tag line as a not-so-subtle hint that Apple will finally be delivering the voice-recognition advances it’s been working on since it acquired Siri nearly 18 months ago — advances some expected to be announced at WWDC 2011 in June.

“In the past,” Munster writes in a note to clients, “Apple has used its invitation to include cryptic hints as to what it will announce. The phrase on this year’s invite, ‘Let’s talk iPhone’ may be a simple play on words, but may also refer to new speech-based features for the iPhone.”

Even more cryptic is the use of the singular “iPhone” and the red number 1 in the telephone icon. “Something tells me there’s only one new iPhone,” posted John Gruber on his Daring Fireball blog. Munster came to the same conclusion, although perhaps by a different route. He writes:

We Do Not Expect a Low-End iPhone. Some investors are looking for Apple to announce a low-end iPhone that Apple could sell to carriers for less than $300 vs. the current carrier cost of over $600. This would enable carriers to offer affordable, unsubsidized iPhones and further penetrate more price-sensitive markets. However, we do not expect Apple to announce such a device on 10/4. Rather, we expect Apple to continue with a lead device (iPhone 5) that carriers sell subsidized for $199/ $299 along with a previous generation device (iPhone 4 or iPhone 4S) for $99.

In any event, we’ll be in Cupertino next Tuesday, live-blogging the proceedings from Apple’s Town Hall Auditorium, the gods of Wi-Fi permitting.