You didn't mention what options you used when you build v8. Unfortunately I don't have any development env available for myself right now, but this source package worked fine for the latest release I made: 

http://pecl.php.net/~jani/v8-3.0.4-1.src.rpm

Also, that missing symbol sounds like something in libstdc++. You do have that around? Try 'ldd v8js.so' to see what libs it's linked with. It may be that you need to put the directory where libstdc++ is into /etc/ld.so.conf (or whatever it was again :)

Thanks for your reply. I built libv8 using scons with no options.

I built v8js.so using the commands: phpize, ./configure, make.

The results of ldd are:
 ldd v8js.so
	linux-gate.so.1 =>  (0x001e7000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x005f5000)
	libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x00614000)
	/lib/ld-linux.so.2 (0x00f48000)

I have libstdc++6.4.4-dev, libstdc++5, libstdc++6 installed. I do not 
know what directory libstdc++ is in. There is a file called 
/etc/ld.so.conf and a folder called /etc/ld.so.conf.d/

What do I need to do?

You propably need to manually link v8js.so with libstdc++ since you didn't build V8 as shared. Building it as shared is better idea though..try that.

I have now built v8 as shared and produced libv8.so which I 
have copied into /usr/lib. When I run make test on v8js I 
still get the error with the undefined symbol _ZdlPv. How 
would I manually link v8js.so with libstdc++?

Okay, now check what that libv8.so was linked with (ldd libv8.so) and same for the new v8js.so you created. Make sure you're loading the correct extension btw. I don't know why it doesn't work for you, it worked fine for me and couple of dozen others. I was using CentOS 5 though with that RPM I provided url to..

Here is the results of ldd for both files:

ldd libv8.so
	linux-gate.so.1 =>  (0x00883000)
	libpthread.so.0 => /lib/tls/i686/cmov/libpthread.so.0 (0x00377000)
	libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00110000)
	libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0x00206000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x0022c000)
	libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x00e23000)
	/lib/ld-linux.so.2 (0x00dca000)



ldd v8js.so 
	linux-gate.so.1 =>  (0x003d6000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00504000)
	libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x006e4000)
	/lib/ld-linux.so.2 (0x00e4e000)

I tried to convert the rpm to a deb file using alien but it failed. I will try and setup a 
CentOS machine to build this on and will also try to build it on windows too. Thanks for your 
help.

Apparently that v8js.so still isn't linked with the shared libv8.so lib, did you remember to remove the static libv8.a before recompiling v8js?

I had forgotten to remove libv8.a and once I had removed 
this, v8js successfully built! Thanks so much for your work 
and your help :)

Ok. I'll leave this report open as building v8js with static libv8 should work as well..

> Ok. I'll leave this report open as building v8js with static libv8 should work as well..

A dynamically linked PHP extension will never work if compiled against static (non-PIC) libv8; closing now.