Suspend to RAM: Yes. Suspend to disk: haven't tried it.
I am using the vanilla kernel 2.6.10 with the ACPI patch from http://acpi.sourceforge.net/
Also, in my suspend script I remove the modules ehci_hcd and uhci_hcd (USB and USB2.0 modules) before going to sleep. Though some people report that they will survive a suspend/resume cycle with the latest kernel.
I don't think the ibm-acpi kernel really plays around with suspend. It is more to get the various function-keys to work etc.
Note: I'm running XFree86 without DRI. I'm waiting for X.org to be officially supported and hopefully better support for the Radeon 7500 card.