1st just let me say, I just recently found SARDU and have really grown fond of it quickly.
Now for the Server 2008 AIO and 7 AIO issue. I've been toying with this for a while now. The biggest hurdle you have is the fat32 file size limitation of 4gb. With that said, you can make your own AIO wim combining any combination of Windows 7/Vista/Server 2008/Server 2008 R2 but you have to be mindful of the size of your install.wim. Just last night I managed to make a combo install.wim of 7 Pro 32 and 64 bit along with Server 2008 R2 Standard. My install.wim came out to be 3.95gb. I chose those 3 systems because that is what I use mostly at work. I'm in the process of testing it now. So far so good. I have 7 Pro 32bit and 64bit working just fine. I still need to check my Server 2008 R2 Standard install though.
These are the instructions I used to combine my Windows 7 and Server 2008 R2 into one setup and only needing the 1 sources folder. It works because Server 2008 R2 not only uses the sources folder in your directory structure, but it also used the sources folder that is inside the install.wim to install correctly.
Now I have seen another instance of someone that made a UDF with 3 partitions. In this case partiton 1 housed some utility apps, antivirus apps, recovery apps and multiple xp and server 2003 installs. (He actually was able to store the xp and 2003 installs as isos and use a driver to load the isos and it works. Partition 2 was Vista SP2 AIO along with Server 2008 AIO. Partition 3 housed Windows 7 and Server 2008 R2 AIO. The UDF did require a minimum of a 16gb flash drive. Unfortunately the user didn't specify how the UDF was built. But I don't think it would be too difficult to figure out. But he used grub4dos as his bootloader and menu system.