[update 04/22/10] There's no video, but anican has a feature on last weekend's MOSAIC.WAV live radio event. Nice pictures! Long story short, MOSAIC.WAV played a few songs, they had a special "animedley" thing going on and DenpaGumi joined in for a few jams as well! Everything went well and they are considering doing more of these live radio events.
[original] On Sunday, April 18 2010, MOSAIC.WAV will hop on the small DearStage... stage... for a live performance. The opening guests are none other than でんぱ組.inc, which makes for a solid lineup. MOSAIC.WAV will also be recording a new episode of their 「モザイク通り」 radio show right in front of their audience. Full details here.
So why should we dirty foreigners care about yet another MOSAIC.WAV gig we'll never see on DVD? Well, DearStage have a very active UStream... stream... which they enable quite often. Unless they receive specific orders from MOSAIC.WAV's legal team not to turn it on, there's a chance it will broadcast a good chunk of the concert. The events start at 4PM Tokyo time, so 3AM Eastern and Midnight Pacific (04/18/10).