Ok, so I have 8gb ram on my machine (aluminum MacBook 2008, dual boot). When I installed Ubuntu, it created a swap partition nearly 9gb in size. I don't know but it seems a bit excessive. Is it safe to resize the swap partition and add it to boot partition?
Yes, it is completely safe to resize your swap and boot partitions (As long as you don't make the boot partition too small.)
A general rule of thumb is that your swap partition should be the same size as the amount of RAM you have in your computer. (In your case, 8000mb)
As a matter of fact, you can technically delete your swap partition altogether. Although this is something I would heavily recommend you not do, it would not cause any significant damage to your system.
Just remember, you will have to resize your partitions from a Live environment, using a partitioning tool such as GParted. If the live environment automatically mounts your swap partition and starts using it, remember to unmount it. In Gparted, you would right-click the swap partition and select "swapoff."