No it doesn't, mine works fine with the 3.0 firmware.
Its just a Nintendo warning to put people off modding, if it were to lock up from a firmware update it will be from ones after 3.0.
All the forums I am joined to concerning the Wii have talked about the 3.0 update with chips and hundreds of people have updated sucessfully including myself with no problems.
The only chip the update is known not to work with so far is Wiip