Since it started delivering them in February, Aruba claims to have shipped 10,000 of its 802.11n access points. We haven't heard comparative figures from any of the other vendors.
The press release doesn't give much else, but it does repeat the new version of Aruba's electrical power claims. At first Aruba said its new access points needed more power for full 3x3 MIMO than 802.3af power over Ethernet could guarantee, but would work on most installations, and fall back to lower speeds when necessary.
Since Siemens claimed full 3x3 MIMO on 802.3af power, Aruba's story has changed. Now, it says "the access points can be powered from a single 802.3af Power-over-Ethernet source and feature 3x3 MIMO operation and ultra-compact packaging."
I notice that the structure of that sentence implies you can power it from 802.3af, and you can also get 3x3 MIMO - but it doesn't necessarily mean it can do both at the same time.
Whatever the ins and outs of that one, the "ultra-compact packaging" is also interesting. Here's a photo of an Aruba AP between APs from Meru (left) and Cisco (right) - the two vendors who got their APs out before Aruba.
Now, Aruba's AP is clearly smaller, and weighs 0.42kg instead of Cisco's 2.3kg. Aruba points to size as a benefit - a small AP is easier to fit, and less likely to fall on your head after you've screwed it to the ceiling.
It's also got a noticeable difference: three antennas, instead of the six sticking out of the Meru AP, and six external antennas which attach to the coax sockets on the Cisco one. Instead of six antennas, Aruba has used dual band antennas, so the 2.4GHz and the 5GHz radio both use the same set of antennas.
Other vendors have started telling me that six antennas are better, as the antennas can't be optimally positioned for both 2.4GHz and 5GHz, but Aruba's Roger Hockaday denies this: "Additional antennas can help only if they are used for antenna diversity, which is not implemented for 11n chipsets. Unless you are looking to mimic a very large dead ant, there’s no difference between 3 or 6."