Actual release of v.Next hasn't been stated as anything more granular than 2011. Being smart about deploying ConfigMgr based on release dates is prudent, but given this broad timeline for release, I wouldn't base any decision on it.
Do you have other driving factors in your organization like Win 7 deployment or anything else that would require functionality in ConfigMgr? IMO, those should drive your adoption of ConfigMgr 07 or waiting for v.Next. One other factor to also consider is
that SMS 2003 is in it's extended support phase meaning that getting direct support from Microsoft with cost you extra.
Jason | http://myitforum.com/cs2/blogs/jsandys | http://blogs.catapultsystems.com/jsandys/default.aspx | Twitter @JasonSandys