After some checking on the
Wales Boundary Commission, I have come to the conclusion that there will be boundary changes and these should be in time for the 07 Assembly elections. See
the Commission Provisional Recommendations (PDF warning) and
Final recommendations (PDF) that suggest that changes apply to both Westminster and Cardiff constituencies and that the final report on boundary changes must be made by the end of 2006, indicating it should be implemented for the 2007 elections.
That said, most of the changes in Wales are relatively minor, and 17 constituencies remain totally untouched with a number of relatively minor changes that involve at most 200 electors. The only significant changes are in the Gwynned and West Clwyd area
Remember of course that Wales is retaining all its 40 seats, and these will continue to be the same in Westminster and Cardiff. The thing in Scotland is that they have had their Westminster seat tally reduced to 59 at the last election. After consultation, the Scottish Parliament decided that it did not want to reduce the number of Scottish Parliament constituencies but retain the present 73, thus implementing the Westminster boundary changes in Scotland is impossible.