encyclo - 7:17 pm on Oct 10, 2010 (gmt 0)
the target attribute of <form> is deprecated
Well, it has been "undeprecated" (which is not a word, but describes best the situation!), so there is no real issue using target on a form tag. Don't hesitate to use it if you need it, browser support is universal.
It won't validate in HTML 4.01 Strict (or XHTML 1.0 Strict), but it will validate as HTML 4.01 Transitional (either in quirks or standards mode) as well as with HTML5.