How about IM update from GTalk in the same mode as the email updates. For those of us on the move who can't use SMS yet, but can access GTalk (e.g. from Blackberry 8000 series etc.), it would seem like a reasonable halfway house. Email is OK, but I don't fancy having a load of sent messages in my work mail account when I could just be banging an XMMP message Brightkite's way :)
I think it would be useful to include a privacy setting selector (drop down box or radio button) on the following pages of the mobile site: check-in and note posting. Editing the privacy setting before a post is somewhat of a hassle as is. It requires browsing to the "Edit privacy" link, then changing your settings, then submitting them. This is a slow process on my frustratingly slow mobile web. It would be much easier to simply submit your preferred privacy setting along with the note or check in. As is, the place search/check in process already takes quite a few clicks and page loads. Anything to alleviate this would be helpful.
I seem to be able to check-in (first block), the second block seems to also be a business search block, the third block seems to be a person-search block. This is not clear to the user, especially when the drop-down does nothing.
clicking on post a note or photo bumps you right back up to the check-in section.
*basically* How do you post a note to your BK stream using the site via Blackberry?