Someone is working on a Metalink downloader with libcurl. Metalink
lists mirrors and checksums in an XML for higher availability and
integrity.

They plan to use it in Wubi, which lets you intall and dual boot
Ubuntu on Windows without creating a new partition. It previously used
NSISdl.
http://ubuntuforums.org/showthread.php?t=338279

"My plugin is working and looks just like NSISdl (both for users and
NSIS programmers). It uses libcurl for the downloading (as planned)
and can download a file from an url now. My plugin can download from
all protocols supported by libcurl (NSISdl can just download from
HTTP).

It is far from done though. I am going to add support for metalinks
(using expat
for xml parsing) and checksums (using hashing code from XySSL). So far
my plugin
takes 186 kB (i.e. without any xml and hashing libs linked in)."

-- 
(( Anthony Bryan
  )) Metalink [ http://www.metalinker.org ]