Sweet Home 3D 2.5 was released on June 21, 2010 with some important bug fixes described in version history.
Better Collada/DAE support
This version fixes a bug in Collada/DAE support and now you can import correctly DAE files exported from Google SketchUp.
Blocking bugs in photo creation
Some users experienced various problems while rendering their home at the two best qualities in the photo creation dialog. The correction proposed in version 2.3 resolved some problems, but introduced some regressions too. I finally found the real origin of this bug and you shouldn't experience any problem.
Improved management of temporary files
Sweet Home 3D uses temporary files at various places to let users the freedom to move the files they open or import when they want. Miserably, these temporary files got deleted by the system under Mac OS X when Sweet Home 3D wasn't closed during a few days, and this behavior prevented some users to save their home. This has been fixed except under Windows where you should avoid using tools that clean automatically temporary files until the Java bug #6962458 is fixed.
Better memory management - step 2
Memory used by textures was optimized (again), and launching successive renderings in the photo creation dialog shouldn't lead to memory leaks anymore. Users that run the Advanced Rendering plug-in should upgrade to version 1.5 too.
A great thank to Hans and db4tech for helping me finding and fixing the bugs in this version.