Last week, I was pursuing a line of thought for a blog entry but didn’t finish it. Turns out, a little weekend visit to a local AT&T store provided fuel to my thesis, anecdotal though it may be.

The idea goes something like this. With Apple’s upcoming iPhone 4.0 release and better support for the enterprise, it would seem to be driving yet another nail in Research In Motion (RIM) and its stronghold on the business sector. Unless your employer is married to a BES system – which is quite possibly the case – you are free to look around and increasingly, IT organizations are supporting the iPhone, or at least not blocking it.

Upon entering the AT&T store, I told the sales representative that I was just browsing but interested in looking at the iPhone. (Like, what else?) We chatted a bit and got onto the topic of what most customers are interested in. He more or less said iPhone is the big winner, dismissing BlackBerries. You can get e-mail just as easily on the iPhone as a BlackBerry, he explained. We spent some time looking at the Android-based Motorola Backflip but I got the impression it’s getting returned a little too often. No doubt about it, the iPhone remains the hero, at least in this sales rep’s eyes. Somehow the topic of the iPhone with Verizon Wireless came up, and he dutifully explained how AT&T’s network is better, so end of story.

Just to be fair, I walked into a Verizon Wireless store shortly before the AT&T store. It offered a lot of interesting devices, including the Motorola Droid. I didn’t spend a lot of time with the BlackBerries, although I have to admit really liking the keyboard on my Curve before shamefully losing it. The Storm 2 does not really intrigue me, having spent too much time with the Storm 1. (My argument that Verizon Wireless/RIM should just give Storm 1 users the Storm 2 and call it even went nowhere with a Verizon customer service agent.)

In a recent conversation with Mort Rosenthal, CEO of Enterprise Mobile, he told me there’s no question the iPhone is cutting into BlackBerry’s success. His company helps enterprises manage their mobile solutions, and a lot of his customers have 3,000 BlackBerries but they’ve gone from 1,000 to 2,000 iPhones. However, he wouldn’t put flowers on RIM’s grave for a long time; it’s a strong, innovative company, he said.

Granted, these conversations of late do not involve a thorough survey. But do you need a survey to tell you that the Storm 2 got drowned out by the Droid last year? That the iPhone is a “really hot” device? That RIM might not be shining as brightly as it once was?

RIM itself seems to be doing OK on the international front. It also made a push on the consumer market right around the same time Apple was starting to make bigger inroads into the enterprise space.

But with each upgrade to its operating system, Apple is getting better at the enterprise game. Apple has garnered the spotlight much of this month with the iPad and the iPhone 4.0 OS preview. RIM executives promise exciting things to come out of their WES event in Orlando, Fla., later this month. For their sake, let’s hope they hit one out of the ballpark – soon.