I have a good size harddrive (200 GB) that allows me to multi-boot my machine with Fedora Core 4 (64 bit edition), Vector (32 bit edition), Slamd64 (64 bit edition), and Gentoo (64 bit edition). They all share the same swap partition without a problem. I'm wondering if they could all share the same /home partition for the same user-the / partition it would not share.

If your /home directory is a separate partition, then in theory this should work (since a well-behaved program doesn't put any platform-depending data into /home). But probably the only way to find out is to try (remember to make a backup before).

/home directory is a separate partition from /

Please excuse me, I'm really interested to know how to install two or more Linux distributions in such a way that they share the same swap. Clearly the swap partition should not reside in / and I would guess you should manually partition the space to install in; however, beyond these conditions, I have no idea about how to force the second installer to appropriate the former foreign swap partition. Could you please describe how concretely did you that? Assume for instance I already have a Debian "sarge" and want to add Fedora Core 4.
Thanks a lot in advance!

Pretty easy if you already have swap setup. My first Linux install was FC4 and the swap was on hda6. When I installed Slamd64, Vector, and Gentoo and got to the part where they wanted you to define your disk setup I selected hda6 as swap.

Actually, on my other pc I had to re-install FC and selected the already made swap space that was also being used by Slackware. In FC when it asks you if you want to auto-partition or manual partition, choose manual partition. Then select at a minimum a / partition and a swap partition. Format the / partition but don't format the swap partition if it was already used.

My swap (in Debian setting) is a logical part of an extended partition (also containing /home, /usr etc). Does this case meet the setup you speak about? As your swap is /hda6 I would guess the answer is positive; isn't it?
Thanks!

My pc came with WinXP-Home taking up an entire 200 GB disk. I re-partitioned with qtparted from a live cd and moved M$ onto a 15 GB partition (hda1-Primary). Then I installed FC4 using the manual partitioning GUI tool they provide to make /boot (hda2-100 MB), /home (hda3-25 GB), / (hda5-20 GB), and swap (hda6-1 GB). Then I used qtparted to partition the rest of my drive into 20-25 GB slices (qtparted would shutdown...or the livecd did....if I tried to partition it all at once but it works if you do one partition at a time). I don't understand the primary, extended and logical parts and don't wanna throw you off....here's my scheme:

Device Boot Start End Blocks Id System
/dev/hda1 * 1 2055 16506756 7 HPFS/NTFS
/dev/hda2 2056 2068 104422+ 83 Linux
/dev/hda3 2069 5128 24579450 83 Linux
/dev/hda4 5129 24321 154167772+ 5 Extended
/dev/hda5 5129 7678 20482843+ 83 Linux
/dev/hda6 7679 7805 1020096 82 Linux swap / Solaris
/dev/hda7 7806 7869 514048+ 83 Linux
/dev/hda8 7870 10480 20972826 83 Linux
/dev/hda9 10481 13091 20972826 83 Linux
/dev/hda10 13092 15702 20972826 83 Linux
/dev/hda11 15703 18313 20972826 83 Linux
/dev/hda12 18314 21315 24113533+ 83 Linux