I have Intel Corporation Ultimate N WiFi Link 5300. Ubuntu 11.04 - the Natty Narwhal
2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:24 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux.
I have experimented lately with hostapd(mode n). Wifi is unstable in this mode(as mentioned above). Without 802.11n link is stable.