Attachment UI survey

YFrog

File upload

Supports Flash enhanced uploader, but only does one at a time.

URL

No preview.

Webcam

Pops up a lightbox using Flash to access webcam for photo or video. Relatively straightforward:

WordPress

Media type select

You have to choose between 'photo', 'video', 'audio', and 'media' ahead. It then pops up a lightbox offering you the same selection options...

File upload

Enhanced flash version and basic uploaders. Enhanced can upload multiple files.

From URL

No live preview, but I believe it uses oEmbed to handle some URL reference types.

From library

Shows media you've previously uploaded/worked with and can reference again; built-in search and thumbnails.

Facebook

The "share" box has some icons for media types to select, which pop up an additional small box below with the detail options. Unlike WordPress's, the resulting dialog is compact, non-modal, and uses hierarchical menus more closely hewn to the data type.

Photos

Upload file

Only one at a time:

(There's also the 'create a gallery' option which seems fancier. Doesn't like my Flashblock setup so doesn't launch for me.)

Webcam

Flash-enhanced webcam option. Inline in the box, with live preview.

Also with gratuitous visual effects:

Video

Video options for single upload & webcam recording are pretty much the same as for photos, but there's no gallery option:

Events

You can create event invitations straight from the sharing screen. Nifty!

Link

For plain links. Does live preview of thumbnail/title/description

Yammer

Very similar to the Facebook view when writing a new message:

File upload

Uploading document and image files works the same, popping up a single-file open dialog immediately:

Then showing a preview section afterwards, with thumbs for images or plain filenames for docs:

Enhanced documents

There's also a separate option to upload a document file to a system allowing multi-user annotations:

However I wasn't able to get this to work yet.

Linking

Polls

Events