Nomar= Big question mark. He was ahead of schedule on starting his rehab, so he could be back sooner than expected. I still say August...but the beginning of it.
Rocco= All-Star Break. He's at extended Spring Training right now getting ready for the season. This should be fairly certain. He may not run enough this year to be of much value, though. A lot of his value was tied up in his power/speed (Aaron Rowandlike) and he'll lack the jets this season.
Bonds= Bigger question mark than Nomar. Nobody really knows. It appears like he's finally beginning to make progress on his knee (fingers crossed). Alou even said that he was hopeful that Bonds would DH soon. Personally, I'm hopeful that he'll return in late July or early August. However, that is barring any setbacks, which have been aplenty thus far in his rehab.
Maggs= Took batting practice recently. The original timetable was 8-12 weeks (from mid-April), so it sounds like the All-Star break is a reasonable expectation for him, too.