This bug has been reported on Ubuntu Launchpad as:
https://bugs.launchpad.net/bugs/479975

After renaming a folder and enter it the folder itself is marked as active (colored) but by hitting 'Enter' again the folder does not open.
Enter has no effect!
In older versions of Thunar you could enter the folder at once by hitting twice 'Enter'...

Ubuntu 9.10
Linux ubuntu 2.6.31-14-generic #48-Ubuntu SMP Fri Oct 16 14:05:01 UTC 2009 x86_64 GNU/Linux
Thunar 1.0.1-1ubuntu2
---
Architecture: amd64

DistroRelease: Ubuntu 10.04

InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100427.1)

NonfreeKernelModules: fglrx

Package: thunar 1.0.1-3ubuntu1

PackageArchitecture: amd64
ProcEnviron:
 PATH=(custom, no user)
 LANG=de_DE.utf8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-22.33-generic 2.6.32.11+drm33.2
Tags: lucid
Uname: Linux 2.6.32-22-generic x86_64