If you happened to take a peek at the small pulldown menu at the top of the RF dialer this morning, you may have noticed a new service offering.

Yes, just in time for the announcement of a whole new iPhone at Apple’s World Wide Developer’ Conference, we’ve added Skype calling to the features available on RF.com.

And you don’t even need a Skype account to make a Skype call with RF.com.

The process is the same as calling a GoogleTalk or MSN Messenger friend with RF.com.

If your Skype “buddy” is online, you can call her by selecting Skype from the RF dialer pulldown menu, and entering her Skype user name in the dialer and clicking “Call”. Alternatively, you can bypass the the pulldown altogether by entering the call recipient’s user name followed by “@skype” (i.e.: SkypeBuddy@skype) and clicking the “Call” button.

As with all other services, you can add your Skype buddy to your list of “Favorites” on the RF dialer to reach her with a single click.

The outgoing call is actually made by RF.com’s own Skype account (which is why you don’t need your own Skype account to make a Skype call with RF.com), but we’ve made it so that the Skype user getting the call is notified, via an IM message immediately before the Skype “phone” rings, who is calling. For now, the recipient sees only your cell phone number, but we’ll be adding your name in the pseudo caller-ID in the future.

One caveat: Because of the way Skype works (its proprietary approach requires that we run a full Skype client on our servers for each current call), and because RF.com is still in Beta, the number of concurrent Skype calls we can handle is not open-ended. So, though we don’t anticipate this to be common, you may, particularly in peak calling times, have to try more than once to connect.

We’ve got creative ways of addressing this limitation that we’ll be implementing soon. And as we continue to grow, we’ll need them.

Tell us how Skype calling is working, and suggest any improvments, in the comments below.

There have been a couple of applications released of late that pack some of the features offered by the RF dialer. The folks behind these apps are tripping over one another trying to be known as the first “real Voice over IP” application for the iPhone.

Apparently, to some developers (and even some bloggers who write about such things, Here’s one, and another, and one more) “real VoIP” on an iPhone can only be achieved when the cell phone bypasses the cellular voice network altogether, and transmits and receives voice on the device over WiFi or the cell phone carrier’s data stream.

That this is “real VoIP” is an absurd notion on a few levels.

First, VoIP has been in use for many years, long before the term entered the realm of common technical lexicon, and well before Packet8, VoicePulse and Vonage — the companies that first offered consumer-level non-computer-bound IP communications services — brought VoIP to the masses. It is more than likely, if you made any international calls using one of the international Ma Bells over the past two decades, that you were on VoIP without even knowing it. The world’s communications giants have been using VoIP to cut their international transmission costs since shortly after the the IP network was established. What Packet8, VoicePulse and Vonage accomplished was to actually bring those cost-savings to the consumer, creating a whole new industry in the process.

Second, the use of the term “real VoIP” is fraught with contradiction. Is it “Real VoIP” when a conversation originates from a data-only connection (on an iPhone, for example), travels over the IP network to a telephone switch, then using analog telephone lines to reach its recipient on a plain old telephone? If so, then why isn’t the reverse — a conversation that originates from the cellular network, connects to a local switch where the stream is digitally converted and transmitted over VoIP to a recipient on an IM network like Google Talk — “real VoIP?”

Either “real VoIP” is a conversation that bypasses the traditional or cellular networks altogether (in which case even those calling themselves a “real VoIP” solution are fibbing), or it is a conversation that is carried somewhere along its path using VoIP.

Until the IP network totally replaces the traditional and cellular network as the method by which telephone calls are transmitted, we believe the latter to be the case (OK, not so coincidentally, making RF.com the first “real VoIP” solution for the iPhone).

But, ultimately, this debate over semantics is a non-starter. In the real world, what matters is what is of use to the most people in most circumstances. In bringing VoIP to the iPhone, we chose to maximize the benefits by following different paths (GSM versus WiFi, Web-based versus native hacks, etc.) than other developers tackling the mobile IP challenge.

We’ll delve into these paths — and the whys and why-nots of each — in this space in the coming days.