Besides, most of the Katrina residents in Houston either don't vote or are either killing each other off as we speak (thanks to the talented efforts of present mayor Bill White)
I won't accuse people of racism, but that quote comes pretty close. Thanks for telling us that those ig'nunt black folk can't vote because they are "too busy killing each other."
Poor choice of wording aside, your argument is flawed. Just because many Katrina evacuees aren't registered to vote now, doesn't mean they won't be in the coming years. And they don't even need to be registered to vote to be counted in the census, which is part of what the post is about.
No Republican who represents a part of Travis County won his seat by more than about 35,000 votes in the last election. Again, I'm not saying that the influx of refugees will surely create a new Democratic seat in the coming years - just that it'll tighten margins, pose headaches and, along with the rapidly growing Latino population throughout south Texas, cause Republicans to divert funds they normally would not be required to.
As far as Colorado goes, the only people who don't seem to understand it are the Colorado Republican Party. Since in the last half decade they have lost the governorship, the state house, the state senate, the congressional delegation, a U.S. senate seat, and now face a candidate for the other U.S. senate seat who is out raising and out-performing theirs, I don't think it is much of a stretch to say that Colorado is trending Democratic and the influx of new voters to the state has a role to play in that - between 2000 and 2005, a net increase of 160,000 new people entered the state and the growth rate of Hispanics was twice that of whites.
Finally, I would not suggest that the increased black population in Baton Rouge means that Baker's seat is in imminent danger. He is too popular among white swing-voters. However, when he retires, an extra 50,000 black voters in the district will help make the race to replace him interesting.
All of these things - LA losing a Republican house seat through redistricting, margins in Republican-held Houston-area house races getting closer, Baker's LA seat being up for grabs when he leaves office and the Democratic Party consolidating power in Colorado and other western states - are long-term trends. No one is saying that they will all happen right away, but over time they all seem quite possible, if not likely.
The bottom line is that migration shifts, including those resulting from Katrina, may in the end help Democrats more than Republicans, with the possibly exception of Mary Landrieu. And even she may be in better shape than people think. The most recent post-Katrina Survey USA poll has her at 54% approve, 42% disapprove, including a decent 47/48 among whites.