I can confirm this on Jaunty last updated 3 days ago.

je@macmini:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 192.168.33.2
netmask 255.255.255.0


je@macmini:~$ uname -a
Linux macmini 2.6.28-11-generic #41-Ubuntu SMP Wed Apr 8 04:38:53 UTC 2009 i686 GNU/Linux


je@macmini:~$ lspci -vvnn
...
01:00.0 Ethernet controller [0200]: Marvell Technology Group Ltd. 88E8053 PCI-E Gigabit Ethernet Controller [11ab:4362] (rev 22)
	Subsystem: Marvell Technology Group Ltd. Device [11ab:5321]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 256 bytes
	Interrupt: pin A routed to IRQ 2301
	Region 0: Memory at 50200000 (64-bit, non-prefetchable) [size=16K]
	Region 2: I/O ports at 1000 [size=256]
	Expansion ROM at 50500000 [disabled] [size=128K]
	Capabilities: <access denied>
	Kernel driver in use: sky2
	Kernel modules: sky2

02:00.0 Ethernet controller [0200]: Atheros Communications Inc. AR242x 802.11abg Wireless PCI Express Adapter [168c:001c] (rev 01)
	Subsystem: Apple Computer Inc. Device [106b:0086]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 256 bytes
	Interrupt: pin A routed to IRQ 17
	Region 0: Memory at 50100000 (64-bit, non-prefetchable) [size=64K]
	Capabilities: <access denied>
	Kernel driver in use: ath5k_pci
	Kernel modules: ath5k
...


tail from syslog:

Apr 12 21:43:26 macmini kernel: [265376.329137] ath5k phy0: noise floor calibration timeout (2417MHz)
Apr 12 21:45:06 macmini kernel: [265476.044560] ath5k phy0: noise floor calibration timeout (2412MHz)
Apr 12 21:45:06 macmini kernel: [265476.458263] ath5k phy0: noise floor calibration timeout (2417MHz)
Apr 12 21:45:08 macmini NetworkManager: <debug> [1239565508.003125] periodic_update(): Roamed from BSSID 00:18:84:10:46:E2 (emcken) to (none) ((none)) 
Apr 12 21:45:20 macmini NetworkManager: <debug> [1239565520.002288] periodic_update(): Roamed from BSSID (none) ((none)) to 00:18:84:10:46:E2 (emcken)



This is how pinging the machine from elsewhere around when the problem shows (notice package loss between 22 and 33):

64 bytes from 192.168.10.148: icmp_seq=13 ttl=64 time=2.40 ms
64 bytes from 192.168.10.148: icmp_seq=14 ttl=64 time=2.74 ms
64 bytes from 192.168.10.148: icmp_seq=15 ttl=64 time=6.59 ms
64 bytes from 192.168.10.148: icmp_seq=16 ttl=64 time=5.82 ms
64 bytes from 192.168.10.148: icmp_seq=17 ttl=64 time=2.54 ms
64 bytes from 192.168.10.148: icmp_seq=18 ttl=64 time=11.4 ms
64 bytes from 192.168.10.148: icmp_seq=19 ttl=64 time=5.22 ms
64 bytes from 192.168.10.148: icmp_seq=20 ttl=64 time=2.69 ms
64 bytes from 192.168.10.148: icmp_seq=21 ttl=64 time=20.0 ms
64 bytes from 192.168.10.148: icmp_seq=22 ttl=64 time=1.82 ms
64 bytes from 192.168.10.148: icmp_seq=33 ttl=64 time=8990 ms
64 bytes from 192.168.10.148: icmp_seq=34 ttl=64 time=7975 ms
64 bytes from 192.168.10.148: icmp_seq=35 ttl=64 time=6976 ms
64 bytes from 192.168.10.148: icmp_seq=36 ttl=64 time=5976 ms
64 bytes from 192.168.10.148: icmp_seq=37 ttl=64 time=4976 ms
64 bytes from 192.168.10.148: icmp_seq=38 ttl=64 time=3976 ms
64 bytes from 192.168.10.148: icmp_seq=39 ttl=64 time=2950 ms
64 bytes from 192.168.10.148: icmp_seq=40 ttl=64 time=1943 ms
64 bytes from 192.168.10.148: icmp_seq=41 ttl=64 time=943 ms
64 bytes from 192.168.10.148: icmp_seq=42 ttl=64 time=2.24 ms
64 bytes from 192.168.10.148: icmp_seq=43 ttl=64 time=3.25 ms
64 bytes from 192.168.10.148: icmp_seq=44 ttl=64 time=2.18 ms
64 bytes from 192.168.10.148: icmp_seq=45 ttl=64 time=2.25 ms

Got the following installed:
wpasupplicant                              0.6.6-2ubuntu1
network-manager                            0.7.1~rc4.1.cf199a964-0ubuntu1