Yes, but you have to know the forum numbers. For example, this URL will search only the ebook uploads threads:
www.mobileread.com/forums/search.php?do=getdaily&include=126,128,138,153
If you substitute the numbers for the threads you're interested in, that should do the trick. You can find the forum numbers by looking at their links in the
Forums List -- the number is the last part of the URL: i.e. the Sony Reader forum is #100.