I tweeted this before, but a blog post is less ephemeral and serves better as a longer-term memory for myself and maybe for others.
The Thinkpad T410s uses the Realtek rtl8192se wireless chip which doesn't play well with Ubuntu Lucid, even with the general release from last week. To get it to work, I had to:
1) Download Linux driver for rtl8192se from this Realtek page.
2) Untar the package, run make and 'make install' as root.
Unfortunately, you'll need to do this every time you upgrade the kernel, unless support for this chipset gets better.