every link from mid-February till today is not taken into Google SERPs calculation. The links I got in December and January are showing up in my link profile.. but those from mid-February, March and April, no.
The links that are listed in either Webmaster Tools or the link: operator are not necessarily counted for ranking purposes. The reverse logic also is true. Just because a link doesn't show in the reports doesn't mean Google isn't counting that link equity in the ranking algorithm.
From what I can see, the reporting features appear to be separate parts of Google's infrastructure from the actual ranking algorithm. At times the disconnect between the two gets dramatic and at other times, not so much.