Due to a SonyEricsson phone that recently passed away, I took a leap of faith and purchased a Windows Smartphone device, primarily because I want push email and I think the BlackBerry OS was beaten beyond death with a fugly stick (yes, I know it's still all the rage with the kiddies these days). Device and OS debates aside, I was pleased to discover that the most recent 3.0 version of Missing Sync for Windows Mobile supports syncing items from Yojimbo, though there is a limit - bookmarks and PDFs don't seem to sync; just text notes (to Missing Sync's credit, however, browser bookmarks can be synchronized through a separate included plugin).
I'm not sure how long it's done this, since I helped test the 2.5 beta back during the summer and I don't remember Yojimbo being on the list. Regardless, it's a welcome addition and alternative to syncing mostly Apple and Microsoft apps, however I should warn you of one more catch: Smartphone devices (which I bought) don't seem to be able to edit these notes (just like they can't edit Office docs either; only view them), though full-fledged Pocket PC/Windows Mobile can edit them just fine. I've found a few 3rd party apps that might be able to overcome this hurdle, though I haven't had the chance to give any of them a run-through just yet. If anyone knows any better, you know what to do.