答案在这里
http://picasa.google.com/support/bin/answer.py?hl=en&answer=...
以前用过，操作链接位置变了。
简单说就是
This feature is currently only available in English.
You can embed a Flash slideshow of any web album. It'll be automatically updated when you make changes to your album. Follow these steps to embed a slideshow:
- On the My Photos page, click your album.
- Click Link to this album on the right-hand side.
- Click Embed Slideshow.
- Choose your slideshow settings, such as image size, captions, and autoplay.
- Once you've chosen your settings, copy the resulting HTML code (Ctrl-C).
- Paste the HTML in the source code for your site (Ctrl-V).
Once the slideshow is embedded in your site, people who click your slideshow will be taken to view your album in Picasa Web Albums.
只有帐号在英文界面下才能用。所以，自己看英文吧。：）
你可临时把帐号界面切换到英文使用这个功能。