From a market perspective, providing a wiki on the desktop goes a step towards enabling the mobile professional to work with wiki content. Lotus Notes is probably most people's experience with replication: content changes are permitted either on the desktop or on servers. When the two connect they share the list of pending changes.

Already there are wikis that provide replication from the handheld to the desktop: I'm currently experimenting with Dog Melon's Note Studio, which has a Palm – Desktop component. I don't know how well it handles conflicts, though this is less of a problem between handheld and desktop (two devices used by the same person) as it would be between a corporate wiki and potentially hundreds of users. Dog Melon also have a Pocket PC – Desktop edition. These cost $50, a bit unnecessary considering the open source options, especially considering that some stuff on my Treo I'd want to sync up to a server.

In July last year, during a quiet period at work, I built out a working prototype of replication between two instances of TWiki using Unison, a file-based replication tool. At the time I was excited about Acrowiki, by Acrocat software (formally called HWiki), a TWiki-markup compatible wiki that works on my Treo 650. Acrocat have gone shy about revealing anything about future versions and I drew conclusion (that they have yet to refute) that they've practically abandoned it. I can't even use the existing version as I'd need it to use files from the SD card in order for my unison solution to work with it.

Exchanging the content between unlike servers involves not just file replication but data transformation too. This problem is well understood by the Messaging Middleware people (I used to work with products such as TIBCO and IBM MQ) and would likely best be served in an XSL transformation mapping gateway. It'd also require an XML represention of each wiki's text. To my knowledge none of them have XML representations butall will export to XHTML as they have to get their content accepted by the browsers. Bayle Shanks did some pioneering work with the wiki-gateway, but I don't know whether that's progressed at all since.

Quite separately I read that Socialtext has built online access in miki a mobile-enabled version of socialtext. That's not replication, however, I imagine that its an appropriate set of skins formatted and laid out for the mobile device.