lid event not recognized by acpi event rules

Confirmed, my Dell D620 suspends on lid close in Feisty but not in Gutsy.

Edit the file as suggested, works right away after restarting

No need restart the box, it's enough write:

sudo /etc/init.d/acpid force-reload
sudo /etc/init.d/acpid restart

Well, that's _very_ strange. "[ /]" should match "space or slash" and I've verified that acpid parses the event correctly and also that regexec matches "button/lid" given the event from /etc/acpi/events/lidbtn.

I've patched event.c, so that it tests each loaded event against "button/lid" and outputs the event in case it matches:
diff -u acpid-1.0.4/event.c acpid-1.0.4/event.c
--- acpid-1.0.4/event.c
+++ acpid-1.0.4/event.c
@@ -283,6 +283,11 @@
                                fclose(fp);
                                return NULL;
                        }
+ if (!regexec(r->event, "button/lid LID 00000080 0000000f", 0, NULL, 0)) {
+ printf("EVENT: '%s'\n", val);
+ printf("MATCH!\n");
+ }
+
                } else if (!strcasecmp(key, "action")) {
                        if (check_escapes(val) < 0) {
                                acpid_log("ERR: can't load file %s\n", file);
Then compiled it just using "make" and started it in debug mode ("./acpid -d") and part of the output confirmed the match:
[Wed Mar 26 23:48:50 2008] DBG: parsing conf file /etc/acpi/events/lidbtn
EVENT: 'button[ /]lid'
MATCH!

So, while I believe you that you experience this problem, of course, there appears to be some other problem.
Does it work for you if you use "event=button[/ ]lid" (changing the order of space and slash)?
Another possibility would be to try "event=button[/[:space:]]lid".

btw: "sudo invoke-rc.d acpid restart" should be enough to reload acpid.

This probably affects "events/sleepbtn" in the same way, which uses "event=button[ /]sleep".