Background: One prominent part of the Langlands program is the conjecture that all motives are automorphic. It is of interest to consider special cases that are more precise, if less sweeping. The idea is to formulate generalized modularity conjectures that are as concrete as the Shimura-Taniyama-Weil conjecture (now the elliptic modularity theorem). The latter gained much in precision, for example, by Weil's experimental observation of the link between the conductor of the elliptic curve and the level of the weight two modular form. As a next step up the dimension ladder it is natural to consider abelian surfaces over ${\mathbb Q}$, in which case one encounters
Yoshida's conjecture: Any irreducible abelian surface $A$ defined over ${\mathbb Q}$ and with End$(A)={\mathbb Z}$ is modular in the sense that associated to each is a holomorphic Siegel modular cusp eigenform $F$ of genus 2, weight 2, and some level $N$, such that its spinor L-function $L_{\rm spin}(F,s)$ agrees with that of the abelian surface $$ L(H^1(A),s) ~=~ L_{\rm spin}(F,s). $$
Questions:
Has Yoshida's conjecture been proven for some classes of abelian surfaces over ${\mathbb Q}$?
Are there lists of abelian surfaces and associated Siegel modular forms that extend the very useful lists constructed by Cremona and Stein for elliptic curves and their associated modular forms?