I've just added USB host mode support for the Galaxy Tabs. ( Can some mod move this post to the Android developer forum and bless me for posting in that forum? I'm happy to answer questions/discuss but I can't post there yet because I just created this account)
[Ugh! because I have less than eight posts I can't include github links - you'll need to linkify yourself... ]
The github site is here:
Documentation on the changes:
The changelist you probably want if you are want to cherry-pick into another kernel tree:
These changes fix a number of bugs in the Samsung host mode software but are probably not well suited for regular end users. I would recommend that developers who are generating Galaxy Tab kernels consider picking up these changes.