I tried the new PROSet 15.2 (did use PROSet 15.1 before), but it does not make a difference: Wake-on-LAN still does not work.
Probably this is as expected, because the only change mentionned in the readme for PROSet 15.2 is the addition of support for a new adapter: Intel(R) 82567V-4 Gigabit Network Connection. The DP55WG has an Intel 82578DM Gigabit (10/100/1000 Mb/s) Ethernet LAN controller, which already was supported.
The drivers for the 82578DM were not changed from 15.1 to 15.2: these are still version 22.214.171.124 for Windows 7 64bit.
Had this problem with my old install, but somehow I managed to get it to go away (Actually i disabled powerstates and powermanagement - not the most enviromental solution)...
Now my Intel SSD 160gb X25-M broke down - it was my boot disk, so a reinstall was unavoidable.
And look and behold - the netadapter bug is back again. Sigh.
I guess the days where "Buy Intel - it just works" actuall was true are long gone.
What a bummer.