Recently I found exactly the same driver bug in RadeonHD on my RadeinHD3850, I've reported for <= Intel-945 about almost a year ago. The bug probably would not be worth mentioning it, however Tungstengraphic's Roland Scheidegger fixed the bug 3 weeks after I've reported it.
The problem seems to be an off-by-one-half problem, causing images which are scaled on the x-axis to be also blurred on the y-axis. The first line is rendered with pixman (reference), the second with Intel-2.8.0pre on my i945GM:
No big deal, unfourtunatly it makes Nimbus look pretty ugly :-(
There is quite a long list of driver bugs and performance problems I reported against the Intel driver in the freedesktop bugzilla. So far a single pipeline related bug has been fixed (and only for i965 and up, not for the i945 I call my own). Even for bugs causing image rendering corruptions in firefox nothing happens.
Despite the fact that the last two stable releases (2.6 & 2.7) can hardly be called "stable" and are driving distributors crazy, there are major performance regressions.
Hopefully that problems will be resolved soon, however time told a different story in the past.