I experience the same problems (Ubuntu 64-bit) as described by first poster; both for the svn version (currently svn 27780) and for the 2.50 alpha 2 downloaded from blender.org.
The program starts, I see the window being built (window border, top window where 'Blender' is written and the min-max-close buttons. Then the Segmentation fault comes in.
When I run the svn-compiled file with gdb, I get the following:
Temporary breakpoint 1 at 0x6c8ca0
[Thread debugging using libthread_db enabled]
Temporary breakpoint 1, 0x000000000006c8ca0 in main()
Program received signal_SIGSEGV, Segmentation Fault.
0x00000000000e316a6 in GHOST_SetTitle ()
#0 0x0...0e316a6 in GHOST_SetTitle ()
#1 0x0...06cac50 in wm_windows_title ()
#2 0x0...06cb607 in wm_window_add_ghostwindows()
#3 0x0...06d62f4 in WM_check ()
#4 0x0...06d77c0 in WM_read_homefile ()
#5 0x0...06cbbac in WM_init ()
#6 0x0...06c8e1a in main ()